Control system of moving agent group and control method thereof

ABSTRACT

Provided is a method for controlling a moving agent group platooning within a building, the method comprising: a sensing step in which a first moving agent among a plurality of moving agents senses an occurrence of a predetermined event during the plurality of moving agents are platooning, wherein the first moving agent leads the platooning of the plurality of moving agents; and a transferring step in which the first moving agent transfers a group control authority to a second moving agent among the plurality of moving agents, wherein the second moving agent just follows the first moving agent; wherein the second moving agent having the group control authority leads movement of remaining moving agents following the second moving agent.

TECHNICAL FIELD

The present disclosure relates to a control system of a moving agent group and a control method thereof.

BACKGROUND ART

Complex structures such as high-level buildings and large facilities have appeared. Thus, various accidents and disasters have not been smoothly coped with. It is difficult to understand all the situations only with CCTV in the buildings. In a dangerous area due to accidents, a professional person (firefighter) may be injured frequently. Therefore, it is necessary to understand the situation in the building more effectively in order to smoothly cope with various accidents and disasters in the building.

DISCLOSURE Technical Problem

The present disclosure is designed to solve the above-mentioned problem. A purpose of the present disclosure is to provide a control system of a moving agent group which can detect an internal situation of a building in real time, and a control method thereof.

Another purpose of the present disclosure is to provide a control system of a moving agent group and a control method thereof in which when an accident occurs while a moving agent group platoons to identify the situation inside the building, a situation report for the accident and a search for the remaining area are performed simultaneously and individually.

Technical Solution

In a first aspect of the present disclosure, there is provided a method for controlling a moving agent group platooning within a building, the method comprising: a sensing step in which a first moving agent among a plurality of moving agents senses an occurrence of a predetermined event during the plurality of moving agents are platooning, wherein the first moving agent leads the platooning of the plurality of moving agents; and a transferring step in which the first moving agent transfers a group control authority to a second moving agent among the plurality of moving agents, wherein the second moving agent just follows the first moving agent; wherein the second moving agent having the group control authority leads movement of remaining moving agents following the second moving agent.

In one implementation of the first aspect, the method further comprises a report step in which, upon transferring the group control authority from the first moving agent to the second moving agent, the first moving agent acting as a third moving agent transmits event-related information to a server, wherein the event-related information is about the sensed event.

In one implementation of the first aspect, the method further comprises a joining step in which the third moving agent joins, as a second moving agent, into one of moving agent groups currently platooning.

In one implementation of the first aspect, the event-related information includes at least one of an event occurrence position, an image of the position, and a type of the event.

In one implementation of the first aspect, the sensing step includes: a group formation step in which a server assigns the group control authority to one of the plurality of moving agents and transmits travel-related information to the moving agent having the group control authority assigned thereto; a platooning step in which while the first moving agent as the moving agent having the group control authority is positioned at a frontmost position, the first moving agent travels according to the travel-related information, and a second moving agent as a remaining moving agent free of the group control authority follows the first moving agent; and a sensing step in which the first moving senses the occurrence of the predetermined event during being traveling according to the travel-related information.

In one implementation of the first aspect, in the group formation step, the server grants the group control authority to each of two or more moving agents among the plurality of moving agents and transmits the travel-related information to each of the two or more moving agents as the first moving agent having the group control authority assigned thereto, thereby form a plurality of moving agent groups, wherein each group control authority includes information about the second moving agent belonging to each of the moving agent groups.

In one implementation of the first aspect, each group control authority includes information about the second moving agent free belonging to each of the moving agent groups, wherein in the platooning step, the first moving agent sends platooning-related information to the second moving agent belonging to a corresponding group according to the group control authority, and the second moving agent travels according to the platooning-related information.

In one implementation of the first aspect, the platooning-related information includes at least one of an ID, a current position, a current operation of the first moving agent.

In one implementation of the first aspect, the platooning step is configured such that the first moving agent determines whether a pre-set group reconstruction requirement is met during is travelling and sends the determination result to the server, wherein the method further includes a group reconstruction step in which, upon determination that the group reconstruction requirement is met, the server additionally grants the group control authority to at least one of the plurality of moving agents.

In one implementation of the first aspect, the sensing step includes: a data collection step in which the first moving agent generates travel data and transmits the travel data to the server; and a map creation step in which the server uses the travel data to create a 3D map within the building; wherein the travel data includes at least one of a map of a travel path of the first moving agent and an image acquired using the travel path.

In a second aspect of the present disclosure, there is provided a system for controlling a moving agent group monitoring an interior of a building, the system comprising: a plurality of moving agents platooning along an internal path of the building; and a server in wireless communication with the plurality of moving agents, wherein the sever is configured to control the plurality of moving agents, wherein the plurality of moving agents includes: a first moving agent having a group control authority and travelling while positioned at a frontmost position of the plurality of moving agents; and at least one second moving agent following the first moving agent.

In one implementation of the second aspect, when the first moving agent detects that a predetermined event has occurred while moving along the path, the first moving agent transfers the group control authority to a just following second moving agent, wherein the just following second moving agent has the group control authority and leads movement of following remaining moving agents.

In a third aspect of the present disclosure, there is provided a method for controlling a moving agent platooning together with a plurality of other moving agents within a building, the method comprising: a first step of determining whether the moving agent has a group control authority; a second step in which upon determination that the moving agent does not have the group control authority, the moving agent operate as a second moving agent following another moving agent having the group control authority among the plurality of other moving agents; a third step in which upon determination that the moving agent has the group control authority, the moving agent operate as a first moving agent to control the platooning while being positioned in front of the plurality of other moving agents; a fourth step in which when the first moving agent detects a preset event during being travelling, the first moving agent transfers the group control authority to a just next following moving agent among the other moving agents.

In one implementation of the third aspect, the method further comprises: a fifth step in which upon transferring the group control authority, the first moving agent transmits event-related information to a server, wherein the event-related information is about the detected event; and a sixth step in which the first moving agent joins, as the second moving agent, a moving agent group currently platooning.

In one implementation of the third aspect, in the third step, the first moving agent generates travel data thereof and transmits the travel data to the server, wherein the travel data includes at least one of a map of a travel path of the first moving agent and an image acquired using the travel path.

In one implementation of the third aspect, in the third step, the first moving agent determines whether a pre-set group reconstruction requirement is met during being travelling, and sends the determination result to the server, wherein whether the group reconstruction requirement is met is determined based on an area inside the building, a complexity inside the building, and a total number of moving agents.

Advantageous Effects

The control method and system of the moving agent group according to the present disclosure may use the platooning of the moving agent group to grasp the situation inside the building in real time. Further, the moving agent detecting the event transfers the group control authority to the following moving agent such that a new moving agent group may be used to continuously search for the interior of the building.

Further, in accordance with the present disclosure, the moving agent that has transferred a group control authority leaves its group and transmits the acquired information at the event occurrence point, such that the detection of events and the search for the remaining regions in the building may be done separately during platooning. Therefore, the situation of the accident (event) occurrence point and the situation of the other regions may be received in real time, such that the current situation of the building and the cause of the accident can be grasped in various ways.

Further, in accordance with the present disclosure, a moving agent that has completed the transmission of event (accident) related information joins back the platooning moving agent group, such that the number of moving agents in the group may be kept constant. Therefore, it is possible to effectively cope with various accidents occurring in the plurality of points in a building.

Further, in accordance with the present disclosure, each of a plurality of moving agent groups may platoon. Thus, the moving agent group can be efficiently managed considering the complexity of the building and the total number of moving agents.

Further, in accordance with the present disclosure, a map may be created using information obtained via the platooning of the moving agent groups. Thus, the situation of the building may be grasped in various ways and further the cause of the accident in the blind spot which cannot be grasped by the existing CCTV may be identified.

Further, in accordance the present disclosure, the identification of the internal situation and accident points of the building may be completed be before the workforce for coping with the accident are deployed. This may reduce the human power and economic resources required to understand the situation inside the building, and may minimize the human damage by utilizing the information as obtained.

DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram of a wireless communication system to which the methods proposed herein may be applied.

FIG. 2 shows an example of a basic operation of an user equipment and a 5G network in a 5G communication system.

FIG. 3 illustrates an example of application operation of an user equipment and a 5G network in a 5G communication system.

FIGS. 4 to 7 show an example of an operation of an user equipment using 5G communication.

FIG. 8 is a diagram illustrating an example of a 3GPP signal transmission/reception method.

FIG. 9 illustrates an SSB structure and FIG. 10 illustrates SSB transmission.

FIG. 11 illustrates an example of a random access procedure.

FIG. 12 shows an example of an uplink grant.

FIG. 13 shows an example of a conceptual diagram of uplink physical channel processing.

FIG. 14 shows an example of an NR slot in which a PUCCH is transmitted.

FIG. 15 is a block diagram of a transmitter and a receiver for hybrid beamforming

FIG. 16 shows an example of beamforming using an SSB and a CSI-RS.

FIG. 17 is a flowchart illustrating an example of a DL BM process using an SSB.

FIG. 18 shows another example of DL BM process using a CSI-RS.

FIG. 19 is a flowchart illustrating an example of a process of determining a reception beam of a UE.

FIG. 20 is a flowchart illustrating an example of a transmission beam determining process of a BS.

FIG. 21 shows an example of resource allocation in time and frequency domains related to an operation of FIG. 21.

FIG. 22 shows an example of a UL BM process using an SRS.

FIG. 23 is a flowchart illustrating an example of a UL BM process using an SRS.

FIG. 24 is a diagram showing an example of a method of indicating a pre-emption.

FIG. 25 shows an example of a time/frequency set of pre-emption indication.

FIG. 26 shows an example of a narrowband operation and frequency diversity.

FIG. 27 is a diagram illustrating physical channels that may be used for MTC and a general signal transmission method using the same.

FIG. 28 is a diagram illustrating an example of scheduling for each of MTC and legacy LTE.

FIG. 29 shows an example of a frame structure when a subcarrier spacing is 15 kHz.

FIG. 30 shows an example of a frame structure when a subscriber spacing is 3.75 kHz.

FIG. 31 shows an example of a resource grid for NB-IoT uplink.

FIG. 32 shows an example of an NB-IoT operation mode.

FIG. 33 is a diagram illustrating an example of physical channels that may be used for NB-IoT and a general signal transmission method using the same.

FIG. 34 is a diagram for describing the configuration of a control system of a moving agent group according to an embodiment of the present disclosure.

FIG. 35 is a diagram for describing the configuration of a moving agent according to another embodiment of the present disclosure.

FIG. 36 is a diagram for describing the detailed configuration of a moving agent according to another embodiment of the present disclosure.

FIG. 37 is a plan view to describe the building in which the moving agent group is deployed.

FIG. 38 is a flow chart for describing the control method of the moving agent group according to another embodiment of the present disclosure.

FIG. 39 is a flow chart for specifically describing the step of detecting the occurrence of an event in the control method of the moving agent group according to another embodiment of the present disclosure.

FIG. 40 is a diagram to describe the operation of the moving agent group in relation to the transfer of the group control authority when a moving agent group detects an event during platooning.

FIG. 41 is a diagram for describing the operation in which a moving agent which has transferred a group control authority when the moving agent group detects the occurrence of an event during platooning joins back the group.

FIG. 42 is a diagram for describing how a plurality of group control authorities are assigned to the moving agents respectively.

FIG. 43 is a diagram for describing how a moving agent group is divided into a plurality of groups during platooning.

FIG. 44 is a diagram for describing a map generated in real time using a server as a moving agent group is platooning.

FIG. 45 is a flow chart for describing the control method of the moving agent according to another embodiment of the present disclosure.

FIG. 46 is a flow chart for describing a detailed operation when a specific moving agent operates as a second moving agent.

FIG. 47 is a flow chart for describing a detailed operation when a specific moving agent operates as a first moving agent.

FIG. 48 is a flow chart for describing a detailed operation when a specific moving agent operates as a third moving agent.

MODE FOR INVENTION

Hereinafter, embodiments of the disclosure will be described in detail with reference to the attached drawings. The same or similar components are given the same reference numbers and redundant description thereof is omitted. The suffixes “module” and “unit” of elements herein are used for convenience of description and thus may be used interchangeably and do not have any distinguishable meanings or functions. Further, in the following description, if a detailed description of known techniques associated with the present invention would unnecessarily obscure the gist of the present invention, detailed description thereof will be omitted. In addition, the attached drawings are provided for easy understanding of embodiments of the disclosure and do not limit technical spirits of the disclosure, and the embodiments should be construed as including all modifications, equivalents, and alternatives falling within the spirit and scope of the embodiments.

While terms, such as “first”, “second”, etc., may be used to describe various components, such components must not be limited by the above terms. The above terms are used only to distinguish one component from another.

When an element is “coupled” or “connected” to another element, it should be understood that a third element may be present between the two elements although the element may be directly coupled or connected to the other element. When an element is “directly coupled” or “directly connected” to another element, it should be understood that no element is present between the two elements.

The singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise.

In addition, in the specification, it will be further understood that the terms “comprise” and “include” specify the presence of stated features, integers, steps, operations, elements, components, and/or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or combinations.

A. EXAMPLE OF AUTONOMOUS VEHICLE AND 5G NETWORK

FIG. 1 is a block diagram of a wireless communication system to which methods proposed in the disclosure are applicable.

Referring to FIG. 1, a device including an autonomous driving module is defined as a first communication device (910 of FIG. 1 and see paragraph N for detailed description), and a processor 911 may perform detailed autonomous driving operations.

Another vehicle or a 5G network communicating with the autonomous driving device is defined as a second communication device (920 of FIG. 1, and see paragraph N for details), and a processor 921 may perform detailed autonomous driving operations.

Details of a wireless communication system, which is defined as including a first communication device, which is an autonomous vehicle, and a second communication device, which is a 5G network, may refer to paragraph N.

B. AI OPERATION USING 5G COMMUNICATION

FIG. 2 shows an example of a basic operation of a user equipment and a 5G network in a 5G communication system.

The UE transmits the specific information transmission to the 5G network (S1).

Then, the 5G network performs 5G processing on the specific information (S2).

In this connection, the 5G processing may include AI processing.

Then, the 5G network transmits a response including the AI processing result to the UE (S3).

FIG. 3 shows an example of application operation of a user terminal and a 5G network in a 5G communication system.

The UE performs an initial access procedure with the 5G network (S20). The initial connection procedure will be described in more detail in paragraph F.

Then, the UE performs a random access procedure with the 5G network (S21). The random access procedure will be described in more detail in paragraph G.

The 5G network transmits an UL grant for scheduling transmission of specific information to the UE (S22). The process of the UE receiving the UL grant will be described in more detail in the UL transmission/reception operation in paragraph H.

Then, the UE transmits specific information to the 5G network based on the UL grant (S23).

Then, the 5G network performs 5G processing on the specific information (S24).

In this connection, the 5G processing may include AI processing.

Then, the 5G network transmits a DL grant for scheduling transmission of the 5G processing result of the specific information to the UE (S25).

Then, the 5G network transmits a response including the AI processing result to the UE based on the DL grant (S26).

In FIG. 3, an example in which the AI operation and the initial connection process, or the random access process and the DL grant reception process are combined with each other has been exemplarily described using the S20 to S26. However, the present invention is not limited thereto.

For example, the initial connection process and/or the random access process may be performed using the process of S20, S22, S23, S24, and S24. In addition, the initial connection process and/or the random access process may be performed using, for example, the process of S21, S22, S23, S24, and S26. Further, the AI operation and the downlink grant reception procedure may be combined with each other using the process of S23, S24, S25, and S26.

C. UE OPERATION USING 5G COMMUNICATION

FIG. 4 to FIG. 7 show an example of the operation of the UE using 5G communication.

Referring first to FIG. 4, the UE performs an initial access procedure with the 5G network based on SSB to obtain DL synchronization and system information (S30).

Then, the UE performs a random access procedure with the 5G network for UL synchronization acquisition and/or UL transmission (S31).

Then, the UE receives an UL grant to the 5G network to transmit specific information (S32).

Then, the UE transmits the specific information to the 5G network based on the UL grant (S33).

Then, the UE receives a DL grant for receiving a response to the specific information from the 5G network (S34).

Then, the UE receives a response including the AI processing result from the 5G network based on the DL grant (S35).

A beam management (BM) process may be added to S30. A beam failure recovery process may be added to S31. A quasi-co location relationship may be added to S32 to S35. Amore detailed description thereof will be described in more detail in paragraph I.

Next, referring to FIG. 5, the UE performs an initial access procedure with the 5G network based on SSB to obtain DL synchronization and system information (S40).

Then, the UE performs a random access procedure with the 5G network for UL synchronization acquisition and/or UL transmission (S41).

Then, the UE transmits the specific information to the 5G network based on a configured grant (S42). A procedure for configuring the grant in place of receiving the UL grant from the 5G network will be described in more detail in paragraph H.

Then, the UE receives a DL grant for receiving a response to the specific information from the 5G network (S43).

Then, the UE receives the response including the AI processing result from the 5G network based on the DL grant (S44).

Next, referring to FIG. 6, the UE performs an initial access procedure with the 5G network based on the SSB to obtain DL synchronization and system information (S50).

Then, the UE performs a random access procedure with the 5G network for UL synchronization acquisition and/or UL transmission (S51).

Then, the UE receives a DownlinkPreemption IE from the 5G network (S52).

The UE receives a DCI format 2_1 including a preamble indication from the 5G network based on the DownlinkPreemption IE (S53).

Then, the UE does not perform (or expect or assume) the reception of the eMBB data using a resource (PRB and/or OFDM symbol) indicated by the pre-emption indication (S54).

The operation related to the preemption indication is described in more detail in paragraph J.

Then, the UE receives an UL grant to the 5G network to transmit the specific information (S55).

Then, the UE transmits the specific information to the 5G network based on the UL grant (S56).

Then, the UE receives a DL grant for receiving a response to the specific information from the 5G network (S57).

Then, the UE receives a response including the AI processing result from the 5G network based on the DL grant (S58).

Next, referring to FIG. 7, the UE performs an initial access procedure with the 5G network based on SSB to obtain DL synchronization and system information (S60).

Then, the UE performs a random access procedure with the 5G network for UL synchronization acquisition and/or UL transmission (S61).

Then, the UE receives an UL grant to the 5G network to transmit the specific information (S62).

The UL grant includes information on the number of repetitions of transmission of the specific information. The specific information is repeatedly transmitted based on the information on the repetition number (S63).

The UE transmits the specific information to the 5G network based on the UL grant.

Then, the iterative transmission of the specific information is performed using the frequency hopping. The first transmission of the specific information may be done using a first frequency resource, and the second transmission of the specific information may be done using a second frequency resource.

The specific information may be transmitted over a narrow band of 6RB (Resource Block) or 1RB (Resource Block).

Then, the UE receives a DL grant for receiving a response to the specific information from the 5G network (S64).

Then, the UE receives a response including the AI processing result from the 5G network based on the DL grant (S65).

The mMTC described in FIG. 7 will be described in more detail in the paragraph K.

D. INTRODUCTION

Hereinafter, downlink (DL) refers to communication from a base station (BS) to user equipment (UE), and uplink (UL) refers to communication from a UE to a BS. In the downlink, a transmitter may be part of the BS and a receiver may be part of the UE. In the uplink, a transmitter may be part of the UE and a receiver may be part of the BS. Herein, the UE may be represented as a first communication device and the BS may be represented as a second communication device. The BS may be replaced with a term such as a fixed station, a Node B, an evolved NodeB (eNB), a next generation nodeB (gNB), a base transceiver system (BTS), an access point (AP), a network or a 5G (5th generation), artificial intelligence (AI) system, a road side unit (RSU), robot, and the like. Also, the UE may be replaced with a terminal, a mobile station (MS), a user terminal (UT), a mobile subscriber station (MSS), a subscriber station (SS), an advanced mobile station (AMS), a wireless terminal (WT), a machine-type communication (MTC) device, a machine-to-machine (M2M) device, a device-to-device (D2D) device, a vehicle, a robot, an AI module, and the like.

Techniques described herein may be used in a variety of wireless access systems such as Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier Frequency Division Multiple Access (SC-FDMA), etc. CDMA may be implemented as a radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA may be implemented as a radio technology such as Global System for Mobile communications (GSM)/General Packet Radio Service (GPRS)/Enhanced Data Rates for GSM Evolution (EDGE). OFDMA may be implemented as a radio technology such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Evolved-UTRA (E-UTRA) etc. UTRA is a part of Universal Mobile Telecommunications System (UMTS). 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) is a part of Evolved UMTS (E-UMTS) using E-UTRA. LTE-Advanced (LTE-A)/LTE-A pro is an evolution of 3GPP LTE. 3GPP NR NR(New Radio or New Radio Access Technology) is an evolution of 3GPP LTE/LTE-A/LTE-A pro.

For clarity, the following description focuses on a 3GPP communication system (e.g., LTE-A, NR), but technical features of the present invention is not limited thereto. LTE refers to technology after 3GPP TS 36.xxx Release 8. In detail, LTE technology after 3GPP TS 36.xxx Release 10 is referred to as LTE-A, and LTE technology after 3GPP TS 36.xxx Release 13 is referred to as LTE-A pro. 3GPP 5G (5th generation) technology refers to technology after TS 36.xxx Release 15 and technology after TS 38.XXX Release 15. The technology after TS 38.xxx Release 15 may be referred to as 3GPP NR, and technology after TS 36.xxx Release 15 may be referred to as enhanced LTE. “xxx” refers to a standard document detail number. LTE/NR may be collectively referred to as a 3GPP system.

In this disclosure, a node refers to a fixed point capable of transmitting/receiving a radio signal through communication with a UE. Various types of BSs may be used as nodes irrespective of the terms thereof. For example, a BS, a node B (NB), an e-node B (eNB), a pico-cell eNB (PeNB), a home eNB (HeNB), a relay, a repeater, etc. may be a node. In addition, the node may not be a BS. For example, the node may be a radio remote head (RRH) or a radio remote unit (RRU). The RRH or RRU generally has a power level lower than a power level of a BS. At least one antenna is installed per node. The antenna may refer to a physical antenna or refer to an antenna port, a virtual antenna, or an antenna group. A node may be referred to as a point.

In this specification, a cell refers to a prescribed geographical area to which one or more nodes provide a communication service. A “cell” of a geographic region may be understood as coverage within which a node can provide a service using a carrier and a “cell” of a radio resource is associated with bandwidth (BW) which is a frequency range configured by the carrier. Since DL coverage, which is a range within which the node is capable of transmitting a valid signal, and UL coverage, which is a range within which the node is capable of receiving the valid signal from the UE, depends upon a carrier carrying the signal, coverage of the node may be associated with coverage of “cell” of a radio resource used by the node. Accordingly, the term “cell” may be used to indicate service coverage by the node sometimes, a radio resource at other times, or a range that a signal using a radio resource can reach with valid strength at other times.

In this specification, communicating with a specific cell may refer to communicating with a BS or a node which provides a communication service to the specific cell. In addition, a DL/UL signal of a specific cell refers to a DL/UL signal from/to a BS or a node which provides a communication service to the specific cell. A node providing UL/DL communication services to a UE is called a serving node and a cell to which UL/DL communication services are provided by the serving node is especially called a serving cell. Furthermore, channel status/quality of a specific cell refers to channel status/quality of a channel or communication link formed between a BS or node which provides a communication service to the specific cell and a UE.

Meanwhile, a “cell” associated with radio resource may be defined as a combination of DL resources and UL resources, that is, a combination of a DL component carrier (CC) and a UL CC. A cell may be configured to be a DL resource alone or a combination of DL resources and UL resources. If carrier aggregation is supported, a linkage between a carrier frequency of a DL resource (or DL CC) and a carrier frequency of a UL resource (or UL CC) may be indicated by system information transmitted through a corresponding cell. Here, the carrier frequency may be the same as or different from a center frequency of each cell or CC. Hereinafter, a cell operating at a primary frequency will be referred to as a primary cell (Pcell) or a PCC, and a cell operating at a secondary frequency will be referred to as a secondary cell (Scell) Or SCC. The Scell may be configured after the UE performs a radio resource control (RRC) connection establishment with the BS to establish an RRC connection therebetween, that is, after the UE is RRC_CONNECTED. Here, RRC connection may refer to a channel through which an RRC of the UE and an RRC of the BS may exchange RRC messages with each other. The Scell may be configured to provide additional radio resources to the UE. Depending on the capabilities of the UE, the Scell may form a set of serving cells for the UE together with the Pcell. In the case of a UE which is in the RRC_CONNECTED state but is not configured in carrier aggregation or does not support carrier aggregation, there is only one serving cell that is only configured as the Pcell.

Cells support unique wireless access technologies. For example, transmission/reception according to LTE radio access technology (RAT) is performed on an LTE cell, and transmission/reception according to 5G RAT is performed on a 5G cell.

A carrier aggregation (CA) system refers to a system for supporting a wide bandwidth by aggregating a plurality of carriers each having a narrower bandwidth than a target bandwidth. A CA system is different from OFDMA technology in that DL or UL communication is performed using a plurality of carrier frequencies each of which forms a system bandwidth (or a channel bandwidth), whereas the OFDM system carries a base frequency band divided into a plurality of orthogonal subcarriers on a single carrier frequency to perform DL or UL communication. For example, in the case of OFDMA or orthogonal frequency division multiplexing (OFDM), one frequency band having a constant system bandwidth is divided into a plurality of subcarriers having a certain subscriber spacing, and information/data is mapped in the plurality of subcarriers, and the frequency band to which the information/data is mapped is unconverted and transmitted as a carrier frequency of the frequency band. In the case of wireless carrier aggregation, frequency bands having their own system bandwidth and carrier frequency may be simultaneously used for communication, and each frequency band used for carrier aggregation may be divided into a plurality of subcarriers having a predetermined subcarrier spacing.

The 3GPP-based communication standard defines DL physical channels corresponding to resource elements carrying information derived from a higher layer of a physical layer (e.g., a medium access control (MAC) layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, a radio resource control (RRC) layer, a service data adaptation protocol (SDAP), and a non-access stratum (NAS) layer and DL physical signals corresponding to resource elements which are used by a physical layer but which do not carry information derived from a higher layer. For example, a physical downlink shared channel (PDSCH), a physical broadcast channel (PBCH), a physical multicast channel (PMCH), a physical control format indicator channel (PCFICH), and a physical downlink control channel (PDCCH) are defined as the DL physical channels, and a reference signal and a synchronization signal are defined as the DL physical signals. A reference signal (RS), also called a pilot, refers to a special waveform of a predefined signal known to both a BS and a UE. For example, a cell-specific RS (CRS), a UE-specific RS, a positioning RS (PRS), channel state information RS (CSI-RS), and a demodulation reference signal (DMRS) may be defined as DL RSs. Meanwhile, the 3GPP-based communication standards define UL physical channels corresponding to resource elements carrying information derived from a higher layer and UL physical signals corresponding to resource elements which are used by a physical layer but which do not carry information derived from a higher layer. For example, a physical uplink shared channel (PUSCH), a physical uplink control channel (PUCCH), and a physical random access channel (PRACH) are defined as the UL physical channels, and a demodulation reference signal (DM RS) for a UL control/data signal and a sounding reference signal (SRS) used for UL channel measurement are defined as the UL physical signals.

In this specification, a physical downlink control channel (PDCCH) and a physical downlink shared channel (PDSCH) may refer to a set of a time-frequency resources or a set of resource elements carrying downlink control information (DCI) and downlink data, respectively. In addition, a physical uplink control channel, a physical uplink shared channel (PUSCH), and a physical random access channel refer to a set of a time-frequency resources or a set of resource elements carrying uplink control information (UCI), uplink data and random access signals, respectively. Hereinafter, UE's transmitting an uplink physical channel (e.g., PUCCH, PUSCH, or PRACH) means transmitting UCI, uplink data, or a random access signal on the corresponding uplink physical channel or through then uplink physical channel. BS's receiving an uplink physical channel may refer to receiving DCI, uplink data, or random access signal on or through the uplink physical channel. BS's transmitting a downlink physical channel (e.g., PDCCH and PDSCH) has the same meaning as transmitting DCI or downlink data on or through the corresponding downlink physical channel. UE's receiving a downlink physical channel may refer to receiving DCI or downlink data on or through the corresponding downlink physical channel.

In this specification, a transport block is a payload for a physical layer. For example, data given to a physical layer from an upper layer or a medium access control (MAC) layer is basically referred to as a transport block.

In this specification, HARQ (Hybrid Automatic Repeat and reQuest) is a kind of error control method. HARQ-acknowledgement (HARQ-ACK) transmitted through the downlink is used for error control on uplink data, and HARQ-ACK transmitted on the uplink is used for error control on downlink data. A transmitter that performs the HARQ operation transmits data (e.g., a transport block, a codeword) and waits for an acknowledgment (ACK). A receiver that performs the HARQ operation sends an acknowledgment (ACK) only when data is properly received, and sends a negative acknowledgment (NACK) if an error occurs in the received data. The transmitter may transmit (new) data if ACK is received, and retransmit data if NACK is received. After the BS transmits scheduling information and data according to the scheduling information, a time delay occurs until the ACK/NACK is received from the UE and retransmission data is transmitted. This time delay occurs due to channel propagation delay and a time taken for data decoding/encoding. Therefore, when new data is sent after the current HARQ process is finished, a blank space occurs in the data transmission due to the time delay. Therefore, a plurality of independent HARQ processes are used to prevent generation of the blank space in data transmission during the time delay period. For example, if there are seven transmission occasions between an initial transmission and retransmission, the communication device may operate seven independent HARQ processes to perform data transmission without a blank space. Utilizing the plurality of parallel HARQ processes, UL/DL transmissions may be performed continuously while waiting for HARQ feedback for a previous UL/DL transmission.

In this specification, channel state information (CSI) refers to information indicating quality of a radio channel (or a link) formed between a UE and an antenna port. The CSI may include at least one of a channel quality indicator (CQI), a precoding matrix indicator (PMI), a CSI-RS resource indicator (CRI), an SSB resource indicator (SSBRI), a layer indicator (LI), a rank indicator (RI), or a reference signal received power (RSRP).

In this specification, frequency division multiplexing (FDM) may refer to transmission/reception of signals/channels/users at different frequency resources, and time division multiplexing (TDM) may refer to transmission/reception of signals/channels/users at different time resources.

In the present invention, a frequency division duplex (FDD) refers to a communication scheme in which uplink communication is performed on an uplink carrier and downlink communication is performed on a downlink carrier wave linked to the uplink carrier, and time division duplex (TDD) refers to a communication scheme in which uplink and downlink communications are performed by dividing time on the same carrier.

For background information, terms, abbreviations, etc. used in the present specification, may refer to those described in standard documents published before the present invention. For example, the following document may be referred:

3GPP LTE

-   -   3GPP TS 36.211: Physical channels and modulation     -   3GPP TS 36.212: Multiplexing and channel coding     -   3GPP TS 36.213: Physical layer procedures     -   3GPP TS 36.214: Physical layer; Measurements     -   3GPP TS 36.300: Overall description     -   3GPP TS 36.304: User Equipment (UE) procedures in idle mode     -   3GPP TS 36.314: Layer 2—Measurements     -   3GPP TS 36.321: Medium Access Control (MAC) protocol     -   3GPP TS 36.322: Radio Link Control (RLC) protocol     -   3GPP TS 36.323: Packet Data Convergence Protocol (PDCP)     -   3GPP TS 36.331: Radio Resource Control (RRC) protocol     -   3GPP TS 23.303: Proximity-based services (Prose); Stage 2     -   3GPP TS 23.285: Architecture enhancements for V2X services     -   3GPP TS 23.401: General Packet Radio Service (GPRS) enhancements         for Evolved Universal Terrestrial Radio Access Network (E-UTRAN)         access     -   3GPP TS 23.402: Architecture enhancements for non-3GPP accesses     -   3GPP TS 23.286: Application layer support for V2X services;         Functional architecture and information flows     -   3GPP TS 24.301: Non-Access-Stratum (NAS) protocol for Evolved         Packet System (EPS); Stage 3     -   3GPP TS 24.302: Access to the 3GPP Evolved Packet Core (EPC) via         non-3GPP access networks; Stage 3     -   3GPP TS 24.334: Proximity-services (ProSe) User Equipment (UE)         to ProSe function protocol aspects; Stage 3     -   3GPP TS 24.386: User Equipment (UE) to V2X control function;         protocol aspects; Stage 3

3GPP NR

-   -   3GPP TS 38.211: Physical channels and modulation     -   3GPP TS 38.212: Multiplexing and channel coding     -   3GPP TS 38.213: Physical layer procedures for control     -   3GPP TS 38.214: Physical layer procedures for data     -   3GPP TS 38.215: Physical layer measurements     -   3GPP TS 38.300: NR and NG-RAN Overall Description     -   3GPP TS 38.304: User Equipment (UE) procedures in idle mode and         in RRC inactive state     -   3GPP TS 38.321: Medium Access Control (MAC) protocol     -   3GPP TS 38.322: Radio Link Control (RLC) protocol     -   3GPP TS 38.323: Packet Data Convergence Protocol (PDCP)     -   3GPP TS 38.331: Radio Resource Control (RRC) protocol     -   3GPP TS 37.324: Service Data Adaptation Protocol (SDAP)     -   3GPP TS 37.340: Multi-connectivity; Overall description     -   3GPP TS 23.287: Application layer support for V2X services;         Functional architecture and information flows     -   3GPP TS 23.501: System Architecture for the 5G System     -   3GPP TS 23.502: Procedures for the 5G System     -   3GPP TS 23.503: Policy and Charging Control Framework for the 5G         System; Stage 2     -   3GPP TS 24.501: Non-Access-Stratum (NAS) protocol for 5G System         (5GS); Stage 3     -   3GPP TS 24.502: Access to the 3GPP 5G Core Network (5GCN) via         non-3GPP access networks     -   3GPP TS 24.526: User Equipment (UE) policies for 5G System         (5GS); Stage 3

E. 3GPP SIGNAL TRANSMISSION/RECEPTION METHOD

FIG. 8 is a diagram illustrating an example of a 3GPP signal transmission/reception method.

Referring to FIG. 8, when a UE is powered on or enters a new cell, the UE performs an initial cell search operation such as synchronization with a BS (S201). For this operation, the UE can receive a primary synchronization channel (P-SCH) and a secondary synchronization channel (S-SCH) from the BS to synchronize with the BS and acquire information such as a cell ID. In LTE and NR systems, the P-SCH and S-SCH are respectively called a primary synchronization signal (PSS) and a secondary synchronization signal (SSS). The initial cell search procedure is described in detail in paragraph F. below.

After initial cell search, the UE can acquire broadcast information in the cell by receiving a physical broadcast channel (PBCH) from the BS. Further, the UE can receive a downlink reference signal (DL RS) in the initial cell search step to check a downlink channel state.

After initial cell search, the UE can acquire more detailed system information by receiving a physical downlink shared channel (PDSCH) according to a physical downlink control channel (PDCCH) and information included in the PDCCH (S202).

Meanwhile, when the UE initially accesses the BS or has no radio resource for signal transmission, the UE can perform a random access procedure (RACH) for the BS (steps S203 to S206). To this end, the UE can transmit a specific sequence as a preamble through a physical random access channel (PRACH) (S203 and S205) and receive a random access response (RAR) message for the preamble through a PDCCH and a corresponding PDSCH (S204 and S206). In the case of a contention-based RACH, a contention resolution procedure may be additionally performed. The random access procedure is described in detail in paragraph G. below.

After the UE performs the above-described process, the UE can perform PDCCH/PDSCH reception (S207) and physical uplink shared channel (PUSCH)/physical uplink control channel (PUCCH) transmission (S208) as normal uplink/downlink signal transmission processes. Particularly, the UE receives downlink control information (DCI) through the PDCCH

The UE monitors a set of PDCCH candidates in monitoring occasions set for one or more control element sets (CORESET) on a serving cell according to corresponding search space configurations. A set of PDCCH candidates to be monitored by the UE is defined in terms of search space sets, and a search space set may be a common search space set or a UE-specific search space set. CORESET includes a set of (physical) resource blocks having a duration of one to three OFDM symbols. A network can configure the UE such that the UE has a plurality of CORESETs. The UE monitors PDCCH candidates in one or more search space sets. Here, monitoring means attempting decoding of PDCCH candidate(s) in a search space. When the UE has successfully decoded one of PDCCH candidates in a search space, the UE determines that a PDCCH has been detected from the PDCCH candidate and performs PDSCH reception or PUSCH transmission on the basis of DCI in the detected PDCCH.

The PDCCH can be used to schedule DL transmissions over a PDSCH and UL transmissions over a PUSCH. Here, the DCI in the PDCCH includes downlink assignment (i.e., downlink grant (DL grant)) related to a physical downlink shared channel and including at least a modulation and coding format and resource allocation information, or an uplink grant (UL grant) related to a physical uplink shared channel and including a modulation and coding format and resource allocation information.

F. INITIAL ACCESS (IA) PROCESS

Synchronization Signal Block (SSB) Transmission and Related Operation

FIG. 9 illustrates an SSB structure. The UE can perform cell search, system information acquisition, beam alignment for initial access, and DL measurement on the basis of an SSB. The SSB is interchangeably used with a synchronization signal/physical broadcast channel (SS/PBCH) bloc.

Referring to FIG. 9, the SSB includes a PSS, an SSS and a PBCH. The SSB is configured in four consecutive OFDM symbols, and a PSS, a PBCH, an SSS/PBCH or a PBCH is transmitted for each OFDM symbol. Each of the PSS and the SSS includes one OFDM symbol and 127 subcarriers, and the PBCH includes 3 OFDM symbols and 576 subcarriers. The PBCH is encoded/decoded on the basis of a polar code and modulated/demodulated according to quadrature phase shift keying (QPSK). The PBCH in the OFDM symbol includes data resource elements (REs) to which a complex modulation value of a PBCH is mapped and DMRS REs to which a demodulation reference signal (DMRS) for the PBCH is mapped. There are three DMRS REs per resource block of the OFDM symbol, and there are three data REs between the DMRS REs.

Cell Search

Cell search refers to a process in which a UE acquires time/frequency synchronization of a cell and detects a cell identifier (ID) (e.g., physical layer cell ID (PCI)) of the cell. The PSS is used to detect a cell ID in a cell ID group and the SSS is used to detect a cell ID group. The PBCH is used to detect an SSB (time) index and a half-frame.

The cell search procedure of the UE may be summarized as shown in Table 1 below.

TABLE 1 Type of Signals Operations 1st step PSS SS/PBCH block (SSB) symbol timing acquisi- tion Cell ID detection within a cell ID group(3 hypothesis) 2nd Step SSS Cell ID group detection (336 hypothesis) 3rd Step PBCH SSB index and Half frame (HF) index DMRS (Slot and frame boundary detection) 4th Step PBCH Time information (80 ms, System Frame Number (SFN), SSB index, HF) Remaining Minimum System Information (RMSI) Control resource set (CORESET)/Search space configuration 5th Step PDCCH and Cell access information PDSCH RACH configuration

There are 336 cell ID groups and there are 3 cell IDs per cell ID group. A total of 1008 cell IDs are present. Information on a cell ID group to which a cell ID of a cell belongs is provided/acquired through an SSS of the cell, and information on the cell ID among 336 cell ID groups is provided/acquired through a PSS.

FIG. 10 illustrates SSB transmission.

The SSB is periodically transmitted in accordance with SSB periodicity. A default SSB periodicity assumed by a UE during initial cell search is defined as 20 ms. After cell access, the SSB periodicity can be set to one of {5 ms, 10 ms, 20 ms, 40 ms, 80 ms, 160 ms} by a network (e.g., a BS). An SSB burst set is configured at a start portion of the SSB period. The SSB burst set includes a 5 ms time window (i.e., half-frame), and the SSB may be transmitted up to N times within the SS burst set. The maximum transmission number L of the SSB may be given as follows according to a frequency band of a carrier wave. One slot includes a maximum of two SSBs.

-   -   For frequency range up to 3 GHz, L=4     -   For frequency range from 3 GHz to 6 GHz, L=8     -   For frequency range from 6 GHz to 52.6 GHz, L=64

A time position of an SSB candidate in the SS burst set may be defined according to a subscriber spacing. The SSB candidate time position is indexed from 0 to L−1 (SSB index) in time order within the SSB burst set (i.e., half-frame).

A plurality of SSBs may be transmitted within a frequency span of a carrier wave. Physical layer cell identifiers of these SSBs need not be unique, and other SSBs may have different physical layer cell identifiers.

The UE may acquire the DL synchronization by detecting the SSB. The UE may identify a structure of the SSB burst set on the basis of the detected SSB (time) index and thus detect a symbol/slot/half-frame boundary. The number of the frame/half-frame to which the detected SSB belongs may be identified using system frame number (SFN) information and half-frame indication information.

Specifically, the UE may acquire a 10-bit SFN for a frame to which the PBCH belongs from the PBCH. Next, the UE may acquire 1-bit half-frame indication information. For example, if the UE detects a PBCH with a half-frame indication bit set to 0, it may determine that the SSB, to which the PBCH belongs, belongs to a first half-frame in the frame, and if the UE detects a PBCH with a half-frame indication bit set to 1, it may determine that the SSB, to which the PBCH belongs, belongs to a second half-frame in the frame. Finally, the UE may acquire an SSB index of the SSB to which the PBCH belongs on the basis of a DMRS sequence and PBCH payload carried by the PBCH.

Acquisition of System Information (SI)

SI is divided into a master information block (MIB) and a plurality of system information blocks (SIBs). The SI other than the MIB may be referred to as remaining minimum system information (RMSI). Details thereof may be referred to the following:

-   -   The MIB includes information/parameters for monitoring the PDCCH         scheduling PDSCH carrying system information block1 (SIB1) and         is transmitted by the BS through the PBCH of the SSB. For         example, the UE may check whether a control resource set         (CORESET) exists for the Type 0-PDCCH common search space on the         basis of the MIB. The Type 0-PDCCH common search space is a kind         of PDCCH search space and is used to transmit a PDCCH for         scheduling an SI message. If the Type 0-PDCCH common search         space is present, the UE may determine (i) a plurality of         contiguous resource blocks and one or more consecutive resource         blocks constituting a CORESET on the basis of information in the         MIB (e.g., pdcch-ConfigSIB1) and (ii) a PDCCH occasion (e.g.,         time domain position for PDCCH reception). If no Type 0-PDCCH         common search space exists, pdcch-ConfigSIB1 provides         information on a frequency location where SSB/SIB1 exists and         information on a frequency range where SSB/SIB1 does not exist.     -   SIB1 includes information related to availability and scheduling         (e.g., transmission periodicity and SI-window size) of the         remaining SIBs (hereinafter, SIBx, x is an integer equal to or         greater than 2). For example, SIB1 may indicate whether the SIBx         is periodically broadcast or provided according to a request         from the UE on an on-demand basis. If SIBx is provided on the         on-demand basis, SIB1 may include information necessary for the         UE to perform the SI request. The SIB1 is transmitted through         the PDSCH, the PDCCH for scheduling the SIB1 is transmitted         through the Type 0-PDCCH common search space, and the SIB1 is         transmitted through the PDSCH indicated by the PDCCH.     -   The SIBx is included in the SI message and transmitted via the         PDSCH. Each SI message is transmitted within a time window         (i.e., SI-window) that occurs periodically.

G. RANDOM ACCESS PROCEDURE

The random access procedure of the UE may be summarized as shown in Table 2 and FIG. 11.

TABLE 2 Signal type Acquired operation/information First PRACH preamble in UL Acquire initial beam step Random selection of random access preamble ID Second Random access response Timing advance information step on PDSCH Random access preamble ID Initial UL grant, temporary C-RNTI Third UL transmission on RRC connection request step PUSCH UE identifier Fourth Contention resolution Temporary C-RNTI on PDCCH for step on DL initial access C-RNTI on PDCCH for RRC CONNECTED UE

The random access procedure is used for various purposes. For example, the random access procedure can be used for network initial access, handover, and UE triggered UL data transmission. A UE can acquire UL synchronization and UL transmission resources through the random access procedure. The random access procedure is classified into a contention-based random access procedure and a contention-free random access procedure.

FIG. 11 illustrates an example of a random access procedure. In particular, FIG. 11 illustrates a contention-based random access procedure.

First, a UE can transmit a random access preamble through a PRACH as Msg1 of a random access procedure in UL.

Random access preamble sequences having different two lengths are supported. A long sequence length 839 is applied to subcarrier spacings of 1.25 kHz and 5 kHz and a short sequence length 139 is applied to subcarrier spacings of 15 kHz, 30 kHz, 60 kHz and 120 kHz.

Multiple preamble formats are defined by one or more RACH OFDM symbols and different cyclic prefixes (and/or guard time). RACH configuration for a cell is included in the system information of the cell and is provided to the UE. The RACH configuration includes information on a subcarrier spacing of the PRACH, available preambles, preamble format, and the like. The RACH configuration includes association information between SSBs and RACH (time-frequency) resources. The UE transmits a random access preamble in the RACH time-frequency resource associated with the detected or selected SSB.

A threshold value of the SSB for the RACH resource association may be set by the network, and RACH preamble is transmitted or retransmitted on the basis of the SSB in which reference signal received power (RSRP) measured on the basis of the SSB satisfies the threshold value. For example, the UE may select one of the SSB (s) satisfying the threshold value and may transmit or retransmit the RACH preamble on the basis of the RACH resource associated with the selected SSB.

When a BS receives the random access preamble from the UE, the BS transmits a random access response (RAR) message (Msg2) to the UE. A PDCCH that schedules a PDSCH carrying a RAR is CRC masked by a random access (RA) radio network temporary identifier (RNTI) (RA-RNTI) and transmitted. Upon detection of the PDCCH masked by the RA-RNTI, the UE can receive a RAR from the PDSCH scheduled by DCI carried by the PDCCH. The UE checks whether the RAR includes random access response information with respect to the preamble transmitted by the UE, that is, Msg1. Presence or absence of random access information with respect to Msg1 transmitted by the UE can be determined according to presence or absence of a random access preamble ID with respect to the preamble transmitted by the UE. If there is no response to Msg1, the UE can retransmit the RACH preamble less than a predetermined number of times while performing power ramping. The UE calculates PRACH transmission power for preamble retransmission on the basis of most recent pathloss and a power ramping counter.

When the random access response information includes timing advance information for UL synchronization and an UL grant, and when a temporary UE receives a random response information regarding the UE itself on the PDSCH, the UE may know timing advance information for UL synchronization, an initial UL grant, and a UE temporary cell RNTI (cell RNTI, C-RNTI). The timing advance information is used to control uplink signal transmission timing. In order to ensure that the PUSCH/PUCCH transmission by the UE is better aligned with the subframe timing at a network end, the network (e.g. BS) may measure a time difference between the PUSCH/PUCCH/SRS reception and subframes and send timing advance information on the basis of the time difference. The UE can perform UL transmission through Msg3 of the random access procedure over a physical uplink shared channel on the basis of the random access response information. Msg3 can include an RRC connection request and a UE ID. The network can transmit Msg4 as a response to Msg3, and Msg4 can be handled as a contention resolution message on DL. The UE can enter an RRC connected state by receiving Msg4.

Meanwhile, the contention-free random access procedure may be performed when the UE performs handover to another cell or BS or when the contention-free random access procedure is requested by a BS command. A basic process of the contention-free random access procedure is similar to the contention-based random access procedure. However, unlike the contention-based random access procedure in which the UE randomly selects a preamble to be used among a plurality of random access preambles, in the case of the contention-free random access procedure, a preamble (hereinafter referred to as a dedicated random access preamble) to be used by the UE is allocated by the BS to the UE. Information on the dedicated random access preamble may be included in an RRC message (e.g., a handover command) or may be provided to the UE via a PDCCH order. When the random access procedure is started, the UE transmits a dedicated random access preamble to the BS. When the UE receives the random access procedure from the BS, the random access procedure is completed.

As mentioned above, the UL grant in the RAR schedules PUSCH transmission to the UE. The PUSCH carrying initial UL transmission based on the UL grant in the RAR will be referred to as Msg3 PUSCH. The content of the RAR UL grant starts at an MSB and ends at a LSB and is given in Table 3.

TABLE 3 RAR UL grant field Number of bits Frequency hopping flag 1 Msg3 PUSCH frequency resource allocation 12 Msg3 PUSCH time resource allocation 4 Modulation and coding scheme (MCS) 4 Transmit power control (TPC) for Msg3 PUSCH 3 CSI request 1

The TPC command is used to determine transmission power of the Msg3 PUSCH and is interpreted, for example, according to Table 4.

TABLE 4 TPC command value [dB] 0 −6 1 −4 2 −2 3 0 4 2 5 4 6 6 7 8

In the contention-free random access procedure, the CSI request field in the RAR UL grant indicates whether the UE includes an aperiodic CSI report in the corresponding PUSCH transmission. A subcarrier spacing for the Msg3 PUSCH transmission is provided by an RRC parameter. The UE will transmit the PRACH and Msg3 PUSCH on the same uplink carrier of the same service providing cell. A UL BWP for Msg3 PUSCH transmission is indicated by SIB1 (SystemInformationBlock1).

H. DL AND UL TRANSMITTING/RECEIVING OPERATIONS

DL Transmitting/Receiving Operation

A downlink grant (also referred to as a downlink assignment) may be divided into (1) dynamic grant and (2) configured grant. The dynamic grant, which is intended to maximize resource utilization, refers to a method of data transmission/reception on the basis of dynamic scheduling by the BS.

The BS schedules downlink transmission through a DCI. The UE receives on the PDCCH the DCI for downlink scheduling (i.e., including scheduling information of the PDSCH) from the BS. DCI format 1_0 or 1_1 may be used for downlink scheduling. The DCI format 1_1 for downlink scheduling may include, for example, the following information: an identifier for DCI format, a bandwidth part indicator, a frequency domain resource assignment, time domain resource assignment, MCS.

The UE may determine a modulation order, a target code rate, and a transport block size for the PDSCH on the basis of the MCS field in the DCI. The UE may receive the PDSCH in time-frequency resource according to frequency domain resource allocation information and time domain resource allocation information.

The DL grant is also referred to as semi-persistent scheduling (SPS). The UE may receive an RRC message including a resource configuration for transmission of DL data from the BS. In the case of the DL SPS, an actual DL configured grant is provided by the PDCCH and is activated or deactivated by the PDCCH. If the DL SPS is configured, at least the following parameters are provided to the UE via RRC signaling from the BS: a configured scheduling RNTI (CS-RNTI) for activation, deactivation and retransmission; and cycle. The actual DL grant of the DL SPS is provided to the UE by the DCI in the PDCCH addressed to the CS-RNTI. The UE activates an SPS associated with the CS-RNTI if specific fields of the DCI in the PDCCH addressed to the CS-RNTI are set to specific values for scheduling activation. The UE may receive downlink data through the PDSCH on the basis of the SPS.

UL Transmitting/Receiving Operation

The BS transmits a DCI including uplink scheduling information to the UE. The UE receives on the PDCCH the DCI for uplink scheduling (i.e., including scheduling information of the PUSCH) from the BS. DCI format 0_0 or 01 may be used for uplink scheduling. The DCI format 0_1 for uplink scheduling may include the following information: an identifier for DCI format, a bandwidth part indicator, a frequency domain resource assignment, a time domain resource assignment, MCS.

The LIE transmits uplink data on the PUSCH on the basis of the DCI. For example, when the UE detects the PDCCH including the DCI format 0_0 or 0_1, the UE transmits the PUSCH according to an instruction based on the DCI. Two transmission schemes are supported for PUSCH transmission: codebook-based transmission and non-codebook-based transmission.

When an RRC parameter ‘txConfig’ receives an RRC message set to ‘codebook’, the UE is configured to a codebook-based transmission. Meanwhile, when an RRC message in which the RRC parameter ‘txConfig’ is set to ‘nonCodebook’ is received, the UE is configured to a non-codebook-based transmission. The PUSCH may be semi-statically scheduled by the DCI format 00, by the DCI format 01, or by RRC signaling.

The uplink grant may be divided into (1) a dynamic grant and (2) a configured grant.

FIG. 12 shows an example of an uplink grant. FIG. 12(a) illustrates an UL transmission process based on the dynamic grant, and FIG. 12(b) illustrates an UL transmission process based on the configured grant.

A dynamic grant, which is to maximize utilization of resources, refers to a data transmission/reception method based on dynamic scheduling by a BS. This means that when the UE has data to be transmitted, the LIE requests uplink resource allocation from the BS and transmits the data using only uplink resource allocated by the BS. In order to use the uplink radio resource efficiently, the BS must know how much data each UE transmits on the uplink. Therefore, the UE may directly transmit information on uplink data to be transmitted to the BS, and the BS may allocate uplink resources to the LIE on the basis of the information. In this case, the information on the uplink data transmitted from the UE to the BS is referred to as a buffer status report (BSR), and the BSR relates to the amount of uplink data stored in a buffer of the UE.

Referring to FIG. 12(a), an uplink resource allocation process for actual data when the UE does not have an uplink radio resource available for transmission of the BSR is illustrated. For example, since the UE which does not have a UL grant cannot available for UL data transmission cannot transmit the BSR through a PUSCH, the UE must request resource for uplink data must by starting transmission of a scheduling request via a PUCCH, and in this case, an uplink resource allocation process of five steps is used.

Referring to FIG. 12(a), if there is no PUSCH resource for transmitting a BSR, the UE first transmits a scheduling request (SR) to the BS in order to be allocated a PUSCH resource. The SR is used by the UE to request the BS for PUSCH resources for uplink transmission when a reporting event occurs but there is no PUSCH resource available to the UE. Depending on whether there is a valid PUCCH resource for the SR, the UE transmits the SR via the PUCCH or initiates a random access procedure. When the UE receives the UL grant from the BS, it transmits the BSR to the BS via the PUSCH resource allocated by the UL grant. The BS checks the amount of data to be transmitted by the UE on the uplink on the basis of the BSR and transmits a UL grant to the UE. The UE receiving the UL grant transmits actual uplink data to the BS through the PUSCH on the basis of the UL grant.

Referring to FIG. 12(b), the UE receives an RRC message including a resource configuration for transmission of UL data from the BS. There are two types of UL-configured grants in the NR system: Type 1 and Type 2. In the case of UL-configured grant type 1, an actual UL grant (e.g., time resource, frequency resource) is provided by RRC signaling, and in the case of Type 2, an actual UL grant is provided by the PDCCH and is activated or deactivated by the PDCCH. If the grant type 1 is configured, at least the following parameters are provided to the UE via RRC signaling from the BS: CS-RNTI for retransmission; periodicity of the configured grant type 1; information about a start symbol index S and a symbol length L for an intra-slot PUSCH; time domain offset representing an offset of the resource for SFN=0 in the time domain; MCS index indicating modulation order, target code rate, and transport block size. If the grant type 2 is configured, at least the following parameters are provided to the UE via RRC signaling from the BS: CS-RNTI for activation, deactivation and retransmission; periodicity of configured grant type 2. The actual UL grant of the configured grant type 2 is provided to the UE by the DCI in the PDCCH addressed to the CS-RNTI. If the specific fields of the DCI in the PDCCH addressed to the CS-RNTI are set to a specific value for scheduling activation, the UE activates the configured grant type 2 associated with the CS-RNTI.

The UE may perform uplink transmission via the PUSCH on the basis of the configured grant according to the type 1 or type 2.

Resources for initial transmission by the configured grant may or may not be shared by one or more UEs.

FIG. 13 shows an example of a conceptual diagram of uplink physical channel processing.

Each of the blocks shown in FIG. 13 may be performed in each module in the physical layer block of a transmission device. More specifically, the uplink signal processing in FIG. 13 may be performed in the processor of the UE/BS described in this specification. Referring to FIG. 13, the uplink physical channel processing may be performed through scrambling, modulation mapping, layer mapping, transform precoding, precoding, resource element mapping, and SC-FDMA signal generation (SC-FDMA signal generation). Each of the above processes may be performed separately or together in each module of the transmission device. The transform precoding is spreading UL data in a special way to reduce a peak-to-average power ratio (PAPR) of a waveform, and is a kind of discrete Fourier transform (DFT). OFDM using a CP together with the transform precoding that performs DFT spreading is called DFT-s-OFDM, and OFDM using a CP without DFT spreading is called CP-OFDM. Transform precoding may optionally be applied if it is enabled for the UL in an NR system. That is, the NR system supports two options for UL waveforms, one of which is CP-OFDM and the other is DFT-s-OFDM. Whether the UE must use the CP-OFDM as a UL transmit waveform or the DFT-s-OFDM as a UL transmit waveform is provided from the BS to the UE via RRC parameters. FIG. 13 is a conceptual diagram of uplink physical channel processing for DFT-s-OFDM. In the case of CP-OFDM, the transform precoding among the processes of FIG. 13 is omitted.

More specifically, the transmission device scrambles coded bits in a codeword by a scrambling module, and then transmits the coded bits through a physical channel. Here, the codeword is acquired by encoding a transport block. The scrambled bits are modulated by a modulation mapping module into complex-valued modulation symbols. The modulation mapping module may modulate the scrambled bits according to a predetermined modulation scheme and arrange the modulated bits as complex-valued modulation symbols representing a position on a signal constellation. pi/2-BPSK (pi/2-Binary Phase Shift Keying), m-PSK (m-Phase Shift Keying) or m-QAM (m-Quadrature Amplitude Modulation) may be used for modulating the coded data. The complex-valued modulation symbols may be mapped to one or more transport layers by a layer mapping module. The complex-valued modulation symbols on each layer may be precoded by a precoding module for transmission on an antenna port. If the transform precoding is enabled, the precoding module may perform precoding after performing transform precoding on the complex-valued modulation symbols as shown in FIG. 13. The precoding module may process the complex-valued modulation symbols in a MIMO manner according to multiple transmission antennas to output antenna-specific symbols, and distribute the antenna-specific symbols to a corresponding resource element mapping module. An output z of the precoding module may be acquired by multiplying an output y of the layer mapping module by a precoding matrix W of N×M. Here, N is the number of antenna ports and M is the number of layers. The resource element mapping module maps the complex-valued modulation symbols for each antenna port to an appropriate resource element in the resource block allocated for transmission. The resource element mapping module may map the complex-valued modulation symbols to appropriate subcarriers and multiplex the same according to users. The SC-FDMA signal generation module (CP-OFDM signal generation module if the transform precoding is disabled) modulates the complex-valued modulation symbol according to a specific modulation scheme, for example, an OFDM scheme, to generate a complex-valued time domain OFDM (Orthogonal Frequency Division Multiplexing) symbol signal. The signal generation module may perform Inverse Fast Fourier Transform (IFFT) on the antenna specific symbol, and a CP may be inserted into the time domain symbol on which the IFFT has been performed. The OFDM symbol undergoes digital-to-analog conversion, upconverting, and the like, and transmitted to a reception device through each transmission antenna. The signal generation module may include an IFFT module and a CP inserter, a digital-to-analog converter (DAC), and a frequency uplink converter.

A signal processing procedure of a reception device may be the reverse of the signal processing procedure of the transmission device. Details thereof may be referred to the above contents and FIG. 13.

Next, the PUCCH will be described.

The PUCCH supports a plurality of formats, and the PUCCH formats may be classified according to symbol duration, payload size, multiplexing, and the like. Table 5 below illustrates PUCCH formats.

TABLE 5 PUCCH length in OFDM Number Format symbols of bits Usage Etc. 0 1-2  ≤2 1 Sequence selection 1 4-14 ≤2 2 Sequence modulation 2 1-2  >2 4 CP-OFDM 3 4-14 >2 8 DFT-s-OFDM(no UE multiplexing) 4 4-14 >2 16 DFT-s-OFDM(Pre DFT orthogonal cover code(OCC))

The PUCCH formats shown in Table 5 may be divided into (1) a short PUCCH and (2) a long PUCCH. PUCCH formats 0 and 2 may be included in the short PUCCH, and PUCCH formats 1, 3 and 4 may be included in the long PUCCH.

FIG. 14 shows an example of an NR slot in which a PUCCH is transmitted.

The UE transmits one or two PUCCHs through serving cells in different symbols in one slot. When the UE transmits two PUCCHs in one slot, at least one of the two PUCCHs has a structure of the short PUCCH.

I. EMBB (ENHANCED MOBILE BROADBAND COMMUNICATION)

In the case of the NR system, a massive multiple input multiple output (MIMO) environment in which the transmit/receive antennas are significantly increased may be considered. That is, as the large MIMO environment is considered, the number of transmit/receive antennas may increase to several tens or hundreds or more. Meanwhile, the NR system supports communication in above 6 GHz band, that is, the millimeter frequency band. However, the millimeter frequency band has a frequency characteristic in which signal attenuation according to a distance is very sharp due to the use of a frequency band which is too high. Therefore, an NR system using the band of 6 GHz or higher uses a beamforming technique in which energy is collected and transmitted in a specific direction, not in all directions, in order to compensate for sudden propagation attenuation characteristics. In the massive MIMO environment, a hybrid type beamforming technique combining an analog beamforming technique and a digital beamforming technique is required depending on a position to which a beamforming weight vector/precoding vector is applied, to reduce complexity of hardware implementation, increase performance using multiple antennas, obtain flexibility of resource allocation, and facilitate beam control for each frequency.

Hybrid Beamforming

FIG. 15 illustrates an example of a block diagram of a transmitter and a receiver for hybrid beamforming.

As a method for forming a narrow beam in a millimeter frequency band, a beam forming scheme in which energy is increased only in a specific direction by transmitting the same signal using a phase difference suitable for a large number of antennas in a BS or a UE is mainly considered. Such beamforming scheme includes digital beamforming to create a phase difference in a digital baseband signal, analog beamforming to create a phase difference in a modulated analog signal using time delay (i.e., cyclic shift), and hybrid beamforming using both digital beamforming and analog beamforming, or the like. If each antenna element has an RF unit (or transceiver unit (TXRU)) to adjust transmission power and phase, independent beamforming is possible for each frequency resource. However, it is not effective in terms of price to install an RF unit in all 100 antenna elements. That is, since the millimeter frequency band requires a large number of antennas to compensate for the sudden attenuation characteristics and digital beamforming requires an RF component (e.g., a digital-to-analog converter (DAC), a mixer, a power amplifier, a linear amplifier, and the like), implementation of digital beamforming in the millimeter frequency band causes the price of the communication device to increase. Therefore, when a large number of antennas are required such as in the millimeter frequency band, the use of analog beamforming or hybrid beamforming is considered. In the analog beamforming scheme, a plurality of antenna elements are mapped to one TXRU and a direction of a beam is adjusted by an analog phase shifter. Such an analog beamforming scheme may generate only one beam direction in the entire band, and thus, it cannot perform frequency selective beamforming (BF). Hybrid BF is an intermediate form of digital BF and analog BF and has B RF units fewer than Q antenna elements. In the case of the hybrid BF, directions of beams that may be transmitted at the same time is limited to B or less, although there is a difference depending on a method of connecting the B RF units and Q antenna elements.

Beam Management (BM)

The BM process includes processes for acquiring and maintaining a set of BS (or a transmission and reception point (TRP)) and/or UE beams that may be used for downlink (DL) and uplink (UL) transmission/reception and may include the following processes and terms.

-   -   beam measurement: operation for BS or UE to measure         characteristic of received beamforming signal.     -   beam determination: operation for BS or UE to select its own Tx         beam/Rx beam.     -   beam sweeping: an operation to cover spatial domain using         transmission and/or reception beam during a predetermined time         interval in a predetermined manner.     -   beam report: an operation for UE to report information of         beamformed signal on the basis of beam measurement.

The BM process may be classified into (1) DL BM process using SSB or CSI-RS and (2) UL BM process using SRS (sounding reference signal). Also, each BM process may include Tx beam sweeping to determine Tx beam and Rx beam sweeping to determine Rx beam.

DL BM Process

The DL BM process may include (1) transmission of beamformed DL RSs (e.g., CSI-RS or SSB) by the BS, and (2) beam reporting by the UE.

Here, the beam report may include a preferred DL RS ID(s) and a corresponding reference signal received power (RSRP). The DL RS ID may be an SSBRI (SSB Resource Indicator) or a CRI (CSI-RS Resource Indicator).

FIG. 16 shows an example of beamforming using SSB and CSI-RS.

As shown in FIG. 16, the SSB beam and the CSI-RS beam may be used for beam measurement. The measurement metric is an RSRP per resource/block. The SSB may be used for coarse beam measurement, and the CSI-RS may be used for fine beam measurement. SSB may be used for both Tx beam sweeping and Rx beam sweeping. Rx beam sweeping using the SSB may be performed by attempting to receive the SSB while the UE changes the Rx beam for the same SSBRI across multiple SSB bursts. Here, one SS burst may include one or more SSBs, and one SS burst set includes one or more SSB bursts.

1. DL BM Using SSB

FIG. 17 is a flowchart illustrating an example of a DL BM process using SSB.

A configuration for beam report using the SSB is performed at the time of channel state information (CSI)/beam configuration in RRC_CONNECTED.

-   -   The UE receives from the BS a CSI-ResourceConfig IE including a         CSI-SSB-ResourceSetList for the SSB resources used for the BM         (S410). The RRC parameter csi-SSB-ResourceSetList represents a         list of SSB resources used for beam management and reporting in         one resource set. Here, the SSB resource set may be configured         to {SSBx1, SSBx2, SSBx3, SSBx4}. The SSB index may be defined         from 0 to 63.     -   The UE receives signals on the SSB resources from the BS on the         basis of the CSI-SSB-ResourceSetList (S420).     -   If the CSI-RS reportConfig associated with reporting on the         SSBRI and reference signal received power (RSRP) is configured,         the UE reports the best SSBRI and its corresponding RSRP to the         BS S430). For example, if the reportQuantity of the CSI-RS         reportConfig IE is set to ‘ssb-Index-RSRP’, the UE reports the         best SSBRI and a corresponding RSRP to the BS.

When the CSI-RS resource is configured in the same OFDM symbol (s) as the SSB and ‘QCL-Type D’ is applicable, the UE may assume that the CSI-RS and the SSB are quasi co-located (QCL-ed) in terms of ‘QCL-TypeD’. Here, QCL-TypeD may refer to QCL-ed between antenna ports in terms of spatial Rx parameter. The same receive beam may be applied when the UE receives signals of a plurality of DL antenna ports in the QCL-TypeD relationship. Details of QCL may refer to a section 4. QCL below.

2. DL BM Using CSI-RS

Referring to the use of CSI-RS, i) if a repetition parameter is set for a specific CSI-RS resource set and TRS_info is not configured, CSI-RS is used for beam management. ii) If the repetition parameter is not set and TRS_info is set, the CSI-RS is used for a tracking reference signal (TRS). Iii) If the repetition parameter is not set and TRS_info is not set, the CSI-RS is used for CSI acquisition.

(RRC Parameter) If the repetition is set to ‘ON’, it relates to a Rx beam sweeping process of the UE. If the repetition is set to ‘ON’, the UE may assume that if NZP-CSI-RS-ResourceSet is configured, signals of at least one CSI-RS resource in the NZP-CSI-RS-ResourceSet are transmitted in the same downlink space domain filter. That is, at least one CSI-RS resource in the NZP-CSI-RS-ResourceSet is transmitted through the same Tx beam. Here, signals of at least one CSI-RS resource in the NZP-CSI-RS-ResourceSet may be transmitted in different OFDM symbols.

Meanwhile, if the repetition is set to ‘OFF’, it relates to a Tx beam sweeping process of the BS. If the repetition is set to ‘OFF’, the UE does not assume that signals of at least one CSI-RS resource in the NZP-CSI-RS-ResourceSet are transmitted in the same downlink spatial domain transmission filter. That is, the signals of at least one CSI-RS resource in the NZP-CSI-RS-ResourceSet are transmitted through different Tx beams. FIG. 18 shows another example of the DL BM process using CSI-RS.

FIG. 18(a) shows a process of Rx beam determination (or refinement) of the UE, and FIG. 18(b) shows a Tx beam sweeping process of the BS. FIG. 18 (a) shows a case where the repetition parameter is set to ‘ON’, and FIG. 18(b) shows a case where the repetition parameter is set to ‘OFF’.

A process of determining the Rx beam of the UE will be described with reference to FIGS. 18(a) and 19.

FIG. 19 is a flowchart illustrating an example of a process of determining a reception beam of a UE.

-   -   The UE receives an NZP CSI-RS resource set IE including the RRC         parameter regarding ‘repetition’ from the BS through RRC         signaling (S610). Here, the RRC parameter ‘repetition’ is set to         ‘ON’.     -   The UE repeatedly receives signals on the resource(s) in the         CSI-RS resource in which the RRC parameter ‘repetition’ is set         to ‘ON’ in different OFDM (s) through the same Tx beam (or DL         space domain transmission filter) of the BS (S620).     -   The UE determines its own Rx beam (S630).     -   The UE omits the CSI reporting (S640). That is, the UE may omit         CSI reporting when the uplink RRC parameter ‘repetition’ is set         to ‘ON’.

A Tx beam determining process of the BS will be described with reference to FIGS. 18(b) and 20.

FIG. 20 is a flowchart illustrating an example of a transmission beam determining process of the BS.

-   -   The UE receives an NZP CSI-RS resource set IE including an RRC         parameter regarding ‘repetition’ from the BS through RRC         signaling (S710). Here, the RRC parameter ‘repetition’ is set to         ‘OFF’ and is related to the Tx beam sweeping process of the BS.     -   The UE receives signals on the resources in the CSI-RS resource         in which the RRC parameter ‘repetition’ is set to ‘OFF’ through         different Tx beams (DL spatial domain transmission filters) of         the BS (S720).     -   The UE selects (or determines) the best beam (S730)     -   The UE reports an ID (e.g., CRI) for the selected beam and         related quality information (e.g., RSRP) to the BS (S740). That         is, the UE reports the CRI and the RSRP to the BS when the         CSI-RS is transmitted for the BM.

FIG. 21 shows an example of resource allocation in time and frequency domains related to the operation of FIG. 18.

When repetition ‘ON’ is set in the CSI-RS resource set, a plurality of CSI-RS resources are repeatedly used by applying the same transmission beam, and when repetition ‘OFF’ is set in the CSI-RS resource set, different CSI-RS resources may be transmitted in different transmission beams.

3. DL BM-Related Beam Indication

The UE may receive a list of up to M candidate transmission configuration indication (TCI) states for at least a quasi co-location (QCL) indication via RRC signaling. Here, M depends on UE capability and may be 64.

Each TCI state may be configured with one reference signal (RS) set. Table 6 shows an example of a TCI-State IE. The TCI-State IE is associated with a quasi co-location (QCL) type corresponding to one or two DL reference signals (RSs).

TABLE 6 -- ASN1START -- TAG-TCI-STATE-START TCI-State ::= SEQUENCE { tci-StateId TCI-StateId, qcl-Type1 QCL-Info, qcl-Type2 QCL-Info OPTIONAL, -- Need R ... } QCL-Info ::= SEQUENCE { cell ServCellIndex OPTIONAL, -- Need R bwp-Id BWP-Id OPTIONAL, -- Cond CSI-RS-Indicated referenceSignal CHOICE { csi-rs NZP-CSI- RS-ResourceId, ssb SSB-Index }, qcl-Type ENUMERATED {typeA, typeB, typeC, typeD}, ... } -- TAG-TCI-STATE-STOP -- ASN1STOP

In Table 6, ‘bwp-Id’ denotes a DL BWP where RS is located, ‘cell’ denotes a carrier where RS is located, ‘referencesignal’ denotes a reference antenna port(s) which is a QCL-ed source for target antenna port(s) or a reference signal including the same. The target antenna port(s) may be CSI-RS, PDCCH DMRS, or PDSCH DMRS.

4. QCL (Quasi-Co Location)

The UE may receive a list including up to M TCI-state configurations to decode the PDSCH according to the detected PDCCH having an intended DCI for the UE and a given cell. Here, M depends on the UE capability.

As illustrated in Table 6, each TCI-State includes a parameter for establishing a QCL relationship between one or two DL RSs and the DM-RS port of the PDSCH. The QCL relationship is configured with a RRC parameter qcl-Type1 for the first DL RS and a qcl-Type2 (if set) for the second DL RS.

The QCL type corresponding to each DL RS is given by the parameter ‘qcl-Type’ in QCL-Info and may have one of the following values:

-   -   ‘QCL-TypeA’: {Doppler shift, Doppler spread, average delay,         delay spread}     -   ‘QCL-TypeB’: {Doppler shift, Doppler spread}     -   ‘QCL-TypeC’: {Doppler shift, average delay}     -   ‘QCL-TypeD’: {Spatial Rx parameter}

For example, when a target antenna port is a specific NZP CSI-RS, corresponding NZP CSI-RS antenna ports may be instructed/configured to be QCL-ed with a specific TRS in terms of QCL-Type A and QCL-ed with a specific SSB in terms of QCL-Type D. The thusly instructed/configured UE may receive the corresponding NZP CSI-RS using a Doppler and delay value measured by the QCL-TypeA TRS and apply a reception beam used for receiving the QCL-TypeD SSB to the corresponding NZP CSI-RS reception.

UL BM Process

In the UL BM, a Tx beam-Rx beam reciprocity (or beam correspondence) may be or may not be established depending on UE implementation. If the Tx beam-Rx beam reciprocity is established in both the BS and the UE, a UL beam pair may be matched through a DL beam pair. However, if the Tx beam-Rx beam reciprocity is not established in either the BS or the UE, a UL beam pair determining process is required, apart from DL beam pair determination.

In addition, even when the BS and the UE maintain beam correspondence, the BS may use the UL BM process for DL Tx beam determination without requesting the UE to report a preferred beam.

The UL BM may be performed through beamformed UL SRS transmission and whether to apply the UL BM of the SRS resource set is configured by the RRC parameter in a (RRC parameter) usage. If the usage is configured as ‘BeamManagement (BM)’, only one SRS resource may be transmitted for each of a plurality of SRS resource sets at a given time instant.

The UE may be configured with one or more sounding reference signal (SRS) resource sets (through RRC signaling, etc.) set by the (RRC parameter) SRS-ResourceSet. For each SRS resource set, K≥1 SRS resources may be set for the UE. Here, K is a natural number, and a maximum value of K is indicated by SRS_capability.

Like the DL BM, the UL BM process may also be divided into Tx beam sweeping of the UE and Rx beam sweeping of the BS.

FIG. 22 shows an example of a UL BM process using SRS.

FIG. 22(a) shows a process of determining Rx beamforming of a BS, and FIG. 22(b) shows a process of sweeping Tx beam of the UE.

FIG. 23 is a flowchart illustrating an example of a UL BM process using SRS.

-   -   The UE receives RRC signaling (e.g., SRS-Config IE) including an         (RRC parameter) usage parameter set to ‘beam management’ from         the BS (S1010). An SRS-Config IE is used for configuration of         SRS transmission. The SRS-Config IE includes a list of         SRS-Resources and a list of SRS-ResourceSets. Each SRS resource         set refers to a set of SRS-resources.     -   The UE determines Tx beamforming for the SRS resource to be         transmitted on the basis of SRS-SpatialRelation Info included in         the SRS-Config IE (S1020). Here, the SRS-SpatialRelation Info is         configured for each SRS resource and indicates whether to apply         the same beamforming as that used in SSB, CSI-RS, or SRS for         each SRS resource.     -   If SRS-SpatialRelationInfo is configured in the SRS resource,         the same beamforming as that used in SSB, CSI-RS, or SRS is         applied and transmitted. However, if SRS-SpatialRelationInfo is         not configured in the SRS resource, the UE randomly determines         the Tx beamforming and transmits the SRS through the determined         Tx beamforming (S1030).

More specifically, regarding P-SRS in which ‘SRS-ResourceConfigType’ is set to ‘periodic’:

i) If the SRS-SpatialRelationInfo is set to ‘SSB/PBCH’, the UE transmits the corresponding SRS by applying the same spatial domain transmission filter (or generated from the corresponding filter) as the spatial domain Rx filter used for receiving SSB/PBCH; or

ii) If the SRS-SpatialRelationInfo is set to ‘CSI-RS’, the UE transmits the SRS by applying the same spatial domain transmission filter used for receiving the CSI-RS; or

iii) When SRS-SpatialRelationInfo is set to ‘SRS’, the UE transmits the corresponding SRS by applying the same spatial domain transmission filter used for transmitting the SRS.

-   -   In addition, the UE may receive or may not receive a feedback on         the SRS from the BS as in the following three cases (S1040).

i) When Spatial_Relation_Info is set for all SRS resources in the SRS resource set, the UE transmits the SRS to the beam indicated by the BS. For example, if Spatial_Relation_Info indicates SSB, CRI, or SRI in which Spatial_Relation_Info is the same, the UE repeatedly transmits the SRS on the same beam.

ii) Spatial_Relation_Info may not be set for all SRS resources in the SRS resource set. In this case, the UE may freely transmit while changing the SRS beamforming.

iii) Spatial_Relation_Info may only be set for some SRS resources in the SRS resource set. In this case, the SRS is transmitted on the indicated beam for the set SRS resource, and for an SRS resource in which Spatial_Relation_Info is not set, the UE may transit the SRS resource by randomly applying Tx beamforming.

A Beam Failure Recovery (BFR) Process

In a beamformed system, a radio link failure (RLF) may occur frequently due to rotation, movement, or beamforming blockage of the UE. Therefore, BFR is supported in NR to prevent frequent occurrence of the RLFs. The BFR is similar to the radio link failure recovery process and may be supported if the UE knows the new candidate beam(s).

For beam failure detection, the BS configures beam failure detection reference signals for the UE, and if the number of times of beam failure indications from the physical layer of the UE reaches a threshold set by the RRC signaling within a period set by the RRC signaling of the BS, the UE declares beam failure.

After the beam failure is detected, the UE triggers a beam failure recovery by initiating a random access procedure on the PCell; and performs beam failure recovery by selecting a suitable beam (If the BS provides dedicated random access resources for certain beams, they are prioritized by the UE). Upon completion of the random access procedure, beam failure recovery is considered to be completed.

J. URLLC (ULTRA-RELIABLE AND LOW LATENCY COMMUNICATION)

The URLLC transmission defined by the NR may refer to transmission for (1) a relatively low traffic size, (2) a relatively low arrival rate, (3) an extremely low latency requirement (e.g., 0.5, 1 ms), (4) relatively short transmission duration (e.g., 2 OFDM symbols), and (5) urgent service/message, etc.

In the case of UL, transmission for a particular type of traffic (e.g., URLLC) needs to be multiplexed with other previously scheduled transmissions (e.g., eMBB) to meet a more stringent latency requirement. In this regard, one method is to give information indicating that a scheduled UE will be preempted for a specific resource, and allow the URLLC UE to use the resource for UL transmission.

Pre-Emption Indication

In the case of NR, dynamic resource sharing between eMBB and URLLC is supported. eMBB and URLLC services may be scheduled on non-overlapping time/frequency resources and URLLC transmission may occur on scheduled resources for ongoing eMBB traffic. The eMBB UE may not know whether PDSCH transmission of the UE is partially punctured and the UE may not be able to decode the PDSCH due to corrupted coded bits. In consideration of this, NR provides a preemption indication.

The preemption indication may also be referred to as an interrupted transmission indication.

With respect to the preamble indication, the UE receives DownlinkPreemption IE through RRC signaling from the BS. Table 7 below shows an example of the DownlinkPreemption IE.

TABLE 7 -- ASN1START -- TAG-DOWNLINKPREEMPTION-START DownlinkPreemption ::= SEQUENCE { int-RNTI RNTI-Value, timeFrequencySet  ENUMERATED {set0, set1}, dci-PayloadSize INTEGER (0..maxINT-DCI-PayloadSize), int-ConfigurationPerServingCell SEQUENCE (SIZE (1..maxNrofServingCells)) OF INT-ConfigurationPerServingCell,  ... } INT-ConfigurationPerServingCell ::= SEQUENCE { servingCellId ServCellIndex, positionInDCI  INTEGER (0..maxINT-DCI-PayloadSize−1) } -- TAG-DOWNLINKPREEMPTION-STOP -- ASN1STOP

If the UE is provided with the DownlinkPreemption IE, the UE is configured with an INT-RNTI provided by a parameter int-RNTI in the DownlinkPreemption IE to monitor a PDCCH conveying the DCI format 2_1. The UE is further configured with a set of serving cells and a corresponding set of locations for fields in the DCI format 2_1 by positionInDCI by an INT-ConfigurationPerServing Cell including a set of serving cell indices provided by a servingCellID, is configured with an information payload size for DCI format 2_1 by dci-PayloadSize, and is configured with granularity of time-frequency resources by timeFrequencySect.

The UE receives the DCI format 2_1 from the BS on the basis of the DownlinkPreemption IE.

If the UE detects the DCI format 2_1 for a serving cell in the set of serving cells, the UE may assume there is no transmission to the UE in PRBs and symbols indicated by the DCI format 2_1 among sets of PRBs and sets of symbols in the last monitoring period before a monitoring period to which the DCI format 21 belongs. For example, referring to FIG. 9A, the UE determines that a signal in the time-frequency resource indicated by pre-emption is not a DL transmission scheduled for the UE itself and decodes data on the basis of signals received in the remaining resource area.

FIG. 24 is a diagram showing an example of an preemption indication method.

A combination of {M,N} is set by the RRC parameter timeFrequencySet. {M, N}={14,1}, {7,2}.

FIG. 25 shows an example of a time/frequency set of a preemption indication.

A 14-bit bitmap for a preemption indication indicates one or more frequency parts (N>=1) and/or one or more time domain parts (M>=1). In the case of {M, N}={14,1}, as shown in FIG. 25(a), 14 parts in the time domain correspond one-to-one to 14 bits of the 14-bit bit map, and a part corresponding to a bit set to 1, among the 14 bits, is part including pre-empted resources. In the case of {M, N}={7,2}, as shown in FIG. 25(b), the time-frequency resources of the monitoring period is divided into seven parts in the time domain and two parts in the frequency domain, so as to be divided into a total of 14 time-frequency parts. The total of 14 time-frequency parts correspond one-to-one to the 14 bits of the 14-bit bitmap, and the part corresponding to the bit set to 1 among the 14 bits includes the pre-empted resources.

K. MMTC (MASSIVE MTC)

The massive machine type communication (mMTC) is one of the 5G scenarios for supporting a hyper-connection service that simultaneously communicates with a large number of UEs. In this environment, the UE intermittently performs communication with a very low transfer rate and mobility. Therefore, mMTC is aimed at how low cost and for how long the UE can be driven. In this regard, MTC and NB-IoT, which are dealt with in 3GPP will be described.

Hereinafter, a case where a transmission time interval of a physical channel is a subframe will be described as an example. For example, a case where a minimum time interval from a start of transmission of one physical channel (e.g., MPDCCH, PDSCH, PUCCH, PUSCH) to a start of transmission of a next physical channel is one subframe will be described as an example. In the following description, the subframe may be replaced by a slot, a mini-slot, or multiple slots.

MTC (Machine Type Communication)

MTC (Machine Type Communication), which is an application that does not require much throughput applicable to M2M (Machine-to-Machine) or IoT (Internet-of-Things), refers to a communication technology adopted to meet the requirements of the IoT service in 3GPP (3rd Generation Partnership Project).

The MTC may be implemented to meet the criteria of (1) low cost & low complexity, (2) enhanced coverage, and (3) low power consumption.

In 3GPP, MTC has been applied since release 10 (3GPP standard document version 10.x.x.) and features of MTC added for each release of 3GPP will be briefly described.

First, the MTC described in 3GPP Release 10 and Release 11 relates to a load control method. The load control method is to prevent IoT (or M2M) devices from suddenly loading the BS. More specifically, 3GPP Release 10 relates to a method of controlling a load by disconnecting IoT devices when the load occurs, and Release 11 relates to a method of preventing connection of the UE in advance by informing the UE about connection to a cell later through system information of the cell. In Release 12, features for low cost MTC are added, for which UE category 0 is newly defined. The UE category is an indicator indicating how much data the UE may handle at a communication modem. A UE in UE category 0 is a UE with a reduced peak data rate and relaxed radio frequency (RF) requirements, thus reducing baseband and RF complexity. In Release 13, a technology called eMTC (enhanced MTC) was introduced, which allows the UE to operate only at 1.08 MHz, a minimum frequency bandwidth supported by legacy LTE, thereby lowering the price and power consumption of the UE.

The contents described hereinafter is features mainly related to eMTC but may also be equally applicable to the MTC, eMTC, 5G (or NR) unless otherwise mentioned. Hereinafter, for convenience of explanation, MTC will be collectively described.

Therefore, the MTC described below may referred to as the enhanced MTC (eMTC), the LTE-M1/M2, BL (bandwidth reduced low complexity/CE (coverage enhanced), non-BL UE (in enhanced coverage), NR MTC, enhanced BL/CE, and the like. That is, the term MTC may be replaced with terms to be defined in the 3GPP standard in the future.

MTC General Features

(1) MTC operates only within a specific system bandwidth (or channel bandwidth).

MTC may use six resource blocks (RBs) in the system band of the legacy LTE as shown in FIG. 26 or use a specific number of RBs in the system band of the NR system. The frequency bandwidth in which the MTC operates may be defined in consideration of a frequency range of NR and subcarrier spacing. Hereinafter, a specific system or frequency bandwidth in which the MTC operates is referred to as an MTC narrowband (NB). In the NR, the MTC may operate in at least one bandwidth part (BWP) or in a specific band of BWP.

MTC follows a narrowband operation to transmit and receive physical channels and signals, and a maximum channel bandwidth in which the MTC UE is operable is reduced to 1.08 MHz or six (LTE) RBs.

The narrowband may be used as a reference unit in resource allocation units of some downlink and uplink channels, and a physical location of each narrowband in the frequency domain may be defined to be different depending on the system bandwidth.

The bandwidth of 1.08 MHz defined in MTC is defined for the MTC UE to follow the same cell search and random access procedure as the legacy UE.

MTC may be supported by cells having a bandwidth (e.g., 10 MHz) much larger than 1.08 MHz but the physical channels and signals transmitted and received by the MTC are always limited to 1.08 MHz. The system with having much larger bandwidth may be legacy LTE, NR systems, 5G systems, and the like.

A narrowband is defined as six non-overlapping consecutive physical resource blocks in the frequency domain.

FIG. 26(a) is a diagram showing an example of a narrowband operation, and FIG. 26(b) is a diagram showing an example of repetition having RF retuning.

Frequency diversity by RF retuning will be described with reference to FIG. 26(b).

Due to narrowband RF, single antenna and limited mobility, the MTC supports limited frequency, space and time diversity. In order to reduce fading and outage, frequency hopping is supported by MTC between different narrow bands by RF retuning.

In MTC, frequency hopping is applied to different uplink and downlink physical channels when repetition is possible. For example, if 32 subframes are used for PDSCH transmission, first 16 subframes may be transmitted on a first narrowband. Here, the RF front end is retuned to another narrow band, and the remaining 16 subframes are transmitted on the second narrow band.

The narrowband of MTC may be set to the UE via system information or DCI (downlink control information) transmitted by the BS.

(2) The MTC operates in a half duplex mode and uses a limited (or reduced) maximum transmit power. The half duplex mode refers to a mode in which a communication device operates only in an uplink or a downlink at one frequency at one time point and operates in a downlink or an uplink at another frequency at another time point. For example, when the communication device operates in the half-duplex mode, the communication device performs communication using the uplink frequency and the downlink frequency, and the communication device may not use the uplink frequency and the downlink frequency at the same time. The communication device divides time to perform uplink transmission through the uplink frequency and the downlink reception by re-tuning to the downlink frequency for another predetermined time.

(3) MTC does not use channels (defined in legacy LTE or NR) that must be distributed over the entire system bandwidth of the legacy LTE or NR. For example, in the MTC, the PDCCH of the legacy LTE is not used because the PDCCH is distributed over the entire system bandwidth. Instead, a new control channel, MPDCCH (MTC PDCCH), is defined in the MTC. The MPDCCH is transmitted/received within a maximum of 6 RBs in the frequency domain.

(4) MTC uses the newly defined DCI format. For example, DCI formats 6-0A, 6-0B, 6-1A, 6-1B, 6-2, etc., may be used as a DCI format for MTC (see 3GPP TS 36.212).

(5) In the case of MTC, a physical broadcast channel (PBCH), a physical random access channel (PRACH), an MTC physical downlink control channel (M-PDCCH), a physical downlink shared channel (PDSCH), a physical uplink control channel (PUCCH), and a physical uplink shared channel (PUSCH) may be repeatedly transmitted. Due to the MTC repeated transmission, an MTC channel may be decoded even when signal quality or power is very poor, such as in an inadequate environment such as a basement, thereby increasing a cell radius and increasing a penetration effect.

(6) In MTC, PDSCH transmission based on PDSCH scheduling (DCI) and PDSCH scheduling may occur in different subframes (cross-subframe scheduling).

(7) In the LTE system, the PDSCH carrying a general SIB1 is scheduled by the PDCCH, whereas all the resource allocation information (e.g., subframe, transport block size, narrowband index) for SIB1 decoding is determined by a parameter of the MIB and no control channel is used for SIB1 decoding of the MTC.

(8) All resource allocation information (subframe, TBS, subband index) for SIB2 decoding is determined by several SIB1 parameters and no control channel for SIB2 decoding of MTC is used.

(9) The MTC supports an extended paging (DRX) cycle. Here, the paging period refers to a period during which the UE must be wake up to check whether there is a paging from a network even when the UE is in a discontinuous reception (DRX) mode in which it does not attempt to receive a downlink signal for power saving.

(10) MTC may use the same PSS (Primary Synchronization Signal)/SSS (Secondary Synchronization Signal)/CRS (Common Reference Signal) used in legacy LTE or NR. In the case of NR, the PSS/SSS is transmitted on an SSB basis, and a tracking RS (TRS) is a cell-specific RS and may be used for frequency/time tracking.

MTC Operation Mode and Level

Next, an MTC operation mode and level will be described. MTC is classified into two operation modes (first mode, second mode) and four different levels for coverage improvement as shown in Table 8 below.

The MTC operation mode is referred to as a CE (Coverage Enhancement) mode. In this case, the first mode may be referred to as a CE mode A, and the second mode may be referred to as a CE mode B.

TABLE 8 Mode Level Description Mode A Level 1 No repetition for PRACH Level 2 Small Number of Repetition for PRACH Mode B Level 3 Medium Number of Repetition for PRACH Level 4 Large Number of Repetition for PRACH

The first mode is defined for small coverage enhancement to support full mobility and CSI (channel state information, in which there is no repetition or fewer repetition times. The second mode is defined for UEs with extremely poor coverage conditions that support CSI feedback and limited mobility, in which a large number of repetitive transmissions is defined. The second mode provides a coverage improvement of up to 15 dB. Each level of MTC is defined differently in the random access procedure and the paging process.

The MTC operation mode is determined by the BS, and each level is determined by the MTC UE. Specifically, the BS transmits RRC signaling including information on the MTC operation mode to the UE. Here, the RRC signaling may be an RRC connection setup message, an RRC connection reconfiguration message or an RRC connection reestablishment message.

Thereafter, the MTC UE determines a level in each operation mode and transmits the determined level to the BS. Specifically, the MTC UE determines a level in an operation mode on the basis of measured channel quality (e.g., reference signal received power (RSRP), reference signal received quality (RSRQ), or signal to interference plus noise ratio (SINR), and transmits an RACH preamble using a PRACH resource (e.g., frequency, time, preamble resource for PRACH) corresponding to the determined level, thereby informing the BS about the determined level.

MTC Guard Period

As discussed above, MTC operates in narrow band. The location of the narrow band used in the MTC may be different for each particular time unit (e.g., subframe or slot). The MTC UE may tune to different frequencies depending on the time units. A certain amount of time is required for frequency retuning, and certain amount of time is defined as a guard period of MTC. That is, a guard period is required when frequency retuning is performed while transitioning from one time unit to the next time unit, and transmission and reception do not occur during the guard period.

MTC Signal Transmission/Reception Method

FIG. 27 is a diagram illustrating physical channels that may be used for MTC and a general signal transmission method using the same.

In step S1001, the MTC UE, which is powered on again or enters a new cell, performs an initial cell search operation such as synchronizing with the BS. To this end, the MTC UE receives a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) from the BS, adjusts synchronization with the BS, and acquires information such as a cell ID. The PSS/SSS used in the initial cell search operation of the MTC may be a PSS/SSS, a resynchronization signal (RSS), or the like of an legacy LTE.

Thereafter, the MTC UE may receive a physical broadcast channel (PBCH) signal from the BS to acquire broadcast information in a cell.

Meanwhile, the MTC UE may receive a downlink reference signal (DL RS) in an initial cell search step to check a downlink channel state. The broadcast information transmitted through the PBCH is a master information block (MIB), and in the LTE, the MIB is repeated by every 10 ms.

Among the bits of the MIB of the legacy LTE, reserved bits are used in MTC to transmit scheduling for a new SIB1-BR (system information block for bandwidth reduced device) including a time/frequency location and a transport block size. The SIB-BR is transmitted directly on the PDSCH without any control channel (e.g., PDCCH, MPDDCH) associated with the SIB-BR.

Upon completion of the initial cell search, the MTC UE may receive an MPDCCH and a PDSCH according to the MPDCCH information to acquire more specific system information in step S1002. The MPDCCH may be transmitted only once or repeatedly. The maximum number of repetitions of the MPDCCH is set to the UE by RRC signaling from the BS.

Thereafter, the MTC UE may perform a random access procedure such as steps S1003 to S1006 to complete the connection to the BS. A basic configuration related to the RACH process of the MTC UE is transmitted by SIB2. In addition, SIB2 includes parameters related to paging. In the 3GPP system, a paging occasion (PO) refers to a time unit in which the UE may attempt to receive paging. The MTC UE attempts to receive the MPDCCH on the basis of a P-RNTI in the time unit corresponding to its PO on the narrowband (PNB) set for paging. The UE that has successfully decoded the MPDCCH on the basis of the P-RNTI may receive a PDSCH scheduled by the MPDCCH and check a paging message for itself. If there is a paging message for itself, the UE performs a random access procedure to access a network.

For the random access procedure, the MTC UE transmits a preamble through a physical random access channel (PRACH) (S1003), and receives a response message (RAR) for the preamble through the MPDCCH and the corresponding PDSCH. (S1004). In the case of a contention-based random access, the MTC UE may perform a contention resolution procedure such as transmission of an additional PRACH signal (S1005) and reception of the MPDCCH signal and corresponding PDSCH signal (S1006). The signals and/or messages Msg 1, Msg 2, Msg 3, and Msg 4 transmitted in the RACH process in the MTC may be repeatedly transmitted, and the repeat pattern is set to be different according to the CE level. Msg1 denotes a PRACH preamble, Msg2 denotes a random access response (RAR), Msg3 denotes UL transmission on the basis of a UL grant included in the RAR, and Msg4 denotes a DL transmission of the BS to Msg3.

For random access, PRACH resources for the different CE levels are signaled by the BS. This provides the same control of a near-far effect on the PRACH by grouping together UEs experiencing similar path loss. Up to four different PRACH resources may be signaled to the MTC UE.

The MTC UE estimates RSRP using a downlink RS (e.g., CRS, CSI-RS, TRS, and the like), and selects one of different PRACH resources (e.g., frequency, time, and preamble resources for PRACH) for the random access on the basis of the measurement result. The RAR for the PRACH and search spaces for the contention resolution messages for PRACH are also signaled at the BS via system information.

The MTC UE that has performed the above-described process may then receive an MPDCCH signal and/or a PDSCH signal (S1007) and transmit a physical uplink shared channel (PUSCH) signal and/or a physical uplink control channel (PUCCH) (S1108) as a general uplink/downlink signal transmission process. The MTC UE may transmit uplink control information (UCI) to the BS through the PUCCH or PUSCH. The UCI may include HARQ-ACK/NACK, scheduling request (SR), and/or CSI.

When RRC connection to the MTC UE is established, the MTC UE monitors the MPDCCH in a search space set to acquire uplink and downlink data allocation and attempts to receive the MDCCH.

In the case of MTC, the MPDCCH and the PDSCH scheduled by the MDCCH are transmitted/received in different subframes. For example, the MPDCCH having the last repetition in subframe #n schedules the PDSCH starting at subframe #n+2. The DCI transmitted by the MPDCCH provides information on how many times the MPDCCH is repeated so that the MTC UE may know when the PDSCH transmission is started. For example, when the DCI in the MPDCCH started to be transmitted from the subframe #n includes information that the MPDCCH is repeated 10 times, a last subframe in which the MPDCCH is transmitted is the subframe #n+9 and transmission of the PDSCH may start at subframe #n+11.

The PDSCH may be scheduled in the same as or different from a narrow band in which the MPDCCH scheduling the PDSCH is present. If the MPDCCH and the corresponding PDSCH are located in different narrow bands, the MTC UE needs to retune the frequency to the narrow band in which the PDSCH is present before decoding the PDSCH.

For uplink data transmission, scheduling may follow the same timing as legacy LTE. For example, the MPDCCH which is lastly transmitted at subframe #n may schedule PUSCH transmission starting at subframe #n+4.

FIG. 28 shows an example of scheduling for MTC and legacy LTE, respectively.

In the legacy LTE, the PDSCH is scheduled using the PDCCH, which uses the first OFDM symbol(s) in each subframe, and the PDSCH is scheduled in the same subframe as the subframe in which the PDCCH is received.

In contrast, the MTC PDSCH is cross-subframe scheduled, and one subframe between the MPDCCH and the PDSCH is used as a time period for MPDCCH decoding and RF retuning. The MTC control channel and data channel may be repeated over a large number of subframes including up to 256 subframes for the MPDCCH and up to 2048 subframes for the PDSCH so that they may be decoded under extreme coverage conditions.

NB-IoT (Narrowband-Internet of Things)

The NB-IoT may refer to a system for supporting low complexity, low power consumption through a system bandwidth (system BW) corresponding to one resource block (RB) of a wireless communication system.

Here, NB-IoT may be referred to as other terms such as NB-LTE, NB-IoT enhancement, enhanced NB-IoT, further enhanced NB-IoT, NB-NR. That is, NB-IoT may be replaced with a term defined or to be defined in the 3GPP standard, and hereinafter, it will be collectively referred to as ‘NB-IoT’ for convenience of explanation.

The NB-IoT is a system for supporting a device (or UE) such as machine-type communication (MTC) in a cellular system so as to be used as a communication method for implementing IoT (i.e., Internet of Things). Here, one RB of the existing system band is allocated for the NB-IoT, so that the frequency may be efficiently used. Also, in the case of NB-IoT, each UE recognizes a single RB as a respective carrier, so that RB and carrier referred to in connection with NB-IoT in the present specification may be interpreted to have the same meaning.

Hereinafter, a frame structure, a physical channel, a multi-carrier operation, an operation mode, and general signal transmission/reception related to the NB-IoT in the present specification are described in consideration of the case of the legacy LTE system, but may also be extendedly applied to a next generation system (e.g., an NR system, etc.). In addition, the contents related to NB-IoT in this specification may be extendedly applied to MTC (Machine Type Communication) oriented for similar technical purposes (e.g., low-power, low-cost, coverage enhancement, etc.).

Hereinafter, a case where a transmission time interval of a physical channel is a subframe are described as an example. For example, a case where a minimum time interval from the start of transmission of one physical channel (e.g., NPDCCH, NPDSCH, NPUCCH, NPUSCH) to the start of transmission of a next physical channel is one subframe will be described, but in the following description, the subframe may be replaced by a slot, a mini-slot, or multiple slots.

Frame Structure and Physical Resource of NB-IoT

First, the NB-IoT frame structure may be configured to be different according to subcarrier spacing. Specifically, FIG. 29 shows an example of a frame structure when a subscriber spacing is 15 kHz, and FIG. 30 shows an example of a frame structure when a subscriber spacing is 3.75 kHz. However, the NB-IoT frame structure is not limited thereto, and NB-IoT for other subscriber spacings (e.g., 30 kHz) may be considered with different time/frequency units.

In addition, although the NB-IoT frame structure on the basis of the LTE system frame structure has been exemplified in the present specification, it is merely for the convenience of explanation and the present invention is not limited thereto. The method described in this disclosure may also be extendedly applied to NB-IoT based on a frame structure of a next-generation system (e.g., NR system).

Referring to FIG. 29, the NB-IoT frame structure for a 15 kHz subscriber spacing may be configured to be the same as the frame structure of the legacy system (e.g., LTE system) described above. For example, a 10 ms NB-IoT frame may include ten 1 ms NB-IoT subframes, and the 1 ms NB-IoT subframe may include two 0.5 ms NB-IoT slots. Further, each 0.5 ms NB-IoT may include 7 OFDM symbols.

Alternatively, referring to FIG. 30, the 10 ms NB-IoT frame may include five 2 ms NB-IoT subframes, the 2 ms NB-IoT subframe may include seven OFDM symbols and one guard period (GP). Also, the 2 ms NB-IoT subframe may be represented by an NB-IoT slot or an NB-IoT RU (resource unit).

Next, physical resources of the NB-IoT for each of downlink and uplink will be described.

First, the physical resources of the NB-IoT downlink may be configured by referring to physical resources of other wireless communication system (e.g., LTE system, NR system, etc.), except that a system bandwidth is limited to a certain number of RBs (e.g., one RB, i.e., 180 kHz). For example, when the NB-IoT downlink supports only the 15-kHz subscriber spacing as described above, the physical resources of the NB-IoT downlink may be configured as resource regions limiting a resource grid of the LTE system shown in FIG. 31 to one RB in the frequency domain.

Next, in the case of the NB-IoT uplink physical resource, the system bandwidth may be limited to one RB as in the case of downlink. For example, if the NB-IoT uplink supports 15 kHz and 3.75 kHz subscriber spacings as described above, a resource grid for the NB-IoT uplink may be expressed as shown in FIG. 31. In this case, the number of subcarriers NULsc and the slot period Tslot in the uplink band in FIG. 31 may be given as shown in Table 9 below.

TABLE 9 Subcarrier spacing NULsc Tslot Δf = 3.75 kHz 48  6144 · Ts Δf = 15 kHz 12 15360 · Ts

In NB-IoT, resource units (RUs) are used for mapping the PUSCH for NB-IoT (hereinafter referred to as NPUSCH) to resource elements. RU may include NUJLsymb*NULslot SC-FDMA symbols in the time domain and include NRUsc number of consecutive subcarriers in the frequency domain. For example, NRUsc and NULsymb may be given by Table 10 below for frame structure type 1, which is a frame structure for FDD, and may be given by Table 11 below for frame structure type 2, which is frame structure for TDD.

TABLE 10 NPUSCH format Δf NRUsc NULslots NULsymb 1 3.75 kHz 1 16 7 15 kHz 1 16 3 8 6 4 12 2 2 3.75 kHz 1 4 15 kHz 1 4

TABLE 11 Supported uplink- downlink NPUSCH config- format Δf urations NRUsc NULslots NULsymb 1 3.75 kHz 1, 4 1 16 7 15 kHz 1, 2, 3, 4, 5 1 16 3 8 6 4 12 2 2 3.75 kHz 1, 4 1 4 15 kHz 1, 2, 3, 4, 5 1 4

Physical Channel of NB-IoT

A BS and/or a UE supporting the NB-IoT may be configured to transmit/receive physical channels and/or physical signals configured separately from the legacy system. Hereinafter, specific contents related to physical channels and/or physical signals supported by the NB-IoT will be described.

An orthogonal frequency division multiple access (OFDMA) scheme may be applied to the NB-IoT downlink on the basis of a subscriber spacing of 15 kHz. Through this, co-existence with other systems (e.g., LTE system, NR system) may be efficiently supported by providing orthogonality between subcarriers. A downlink physical channel/signal of the NB-IoT system may be represented by adding ‘N (Narrowband)’ to distinguish it from the legacy system. For example, a downlink physical channel may be referred to as an NPBCH (narrowband physical broadcast channel), an NPDCCH (narrowband physical downlink control channel), or an NPDSCH (narrowband physical downlink shared channel), and a downlink physical signal may be referred to as an NPSS (narrowband primary synchronization signal), an NSSS (narrowband secondary synchronization signal), an NRS (narrowband reference signal), an NPRS (narrowband positioning reference signal), an NWUS (narrowband wake up signal), and the like. Generally, the downlink physical channels and physical signals of the NB-IoT may be configured to be transmitted on the basis of a time domain multiplexing scheme and/or a frequency domain multiplexing scheme. In the case of NPBCH, NPDCCH, NPDSCH, etc., which are the downlink channels of the NB-IoT system, repetition transmission may be performed for coverage enhancement. In addition, the NB-IoT uses a newly defined DCI format. For example, the DCI format for NB-IoT may be defined as DCI format NO, DCI format N1, DCI format N2, and the like.

In the NB-IoT uplink, a single carrier frequency division multiple access (SC-FDMA) scheme may be applied on the basis of a subscriber spacing of 15 kHz or 3.75 kHz. As mentioned in the downlink section, the physical channel of the NB-IoT system may be expressed by adding ‘N (Narrowband)’ to distinguish it from the existing system. For example, the uplink physical channel may be represented by a narrowband physical random access channel (NPRACH) or a narrowband physical uplink shared channel (NPUSCH), and the uplink physical signal may be represented by a narrowband demodulation reference signal (NDMRS), or the like. NPUSCH may be divided into NPUSCH format 1 and NPUSCH format 2. In one example, NPUSCH Format 1 may be used for uplink shared channel (UL-SCH) transmission (or transport), and NPUSCH Format 2 may be used for uplink control information transmission such as HARQ ACK signaling. In the case of NPRACH, which is an uplink channel of the NB-IoT system, repetition transmission may be performed for coverage enhancement. In this case, repetition transmission may be performed by applying frequency hopping.

Multi-Carrier Operation of NB-IoT

Next, a multi-carrier operation of the NB-IoT will be described. The multicarrier operation may refer to that multiple carriers set for different uses (i.e., different types) are used for transmitting/receiving channels and/or signals between the BS and/or UE in the NB-Iot.

The NB-IoT may operate in a multi-carrier mode. Here, in the NB-IoT, a carrier wave in the N-Iot may be classified as an anchor type carrier (i.e., an anchor carrier, an anchor PRB) and a non-anchor type carrier a non-anchor type carrier (i.e., non-anchor carrier).

The anchor carrier may refer to a carrier that transmits NPSS, NSSS, NPBCH, and NPDSCH for a system information block (N-SIB) for initial access from a point of view of the BS. That is, in NB-IoT, the carrier for initial access may be referred to as an anchor carrier and the other(s) may be referred to as a non-anchor carrier. Here, only one anchor carrier wave may exist in the system, or there may be a plurality of anchor carrier waves.

Operation Mode of NB-IoT

Next, an operation mode of the NB-IoT will be described. In the NB-IoT system, three operation modes may be supported. FIG. 32 shows an example of operation modes supported in the NB-IoT system. Although the operation mode of the NB-IoT is described herein on the basis of an LTE band, this is for convenience of explanation and may be extendedly applied to other system bands (e.g. NR system band).

Specifically, FIG. 32(a) shows an example of an in-band system, FIG. 32 (b) shows an example of a guard-band system, and FIG. 32(c) Represents an example of a stand-alone system. In this case, the in-band system may be expressed as an in-band mode, the guard-band system may be expressed as a guard-band mode, and the stand-alone system may be expressed in a stand-alone mode.

The in-band system may refer to a system or mode that uses a specific RB in the (legacy) LTE band. The in-band system may be operated by allocating some resource blocks of the LTE system carrier.

A guard-band system may refer to a system or mode that uses NB-IoT in a space reserved for a guard-band of the legacy LTE band. The guard-band system may be operated by allocating a guard-band of an LTE carrier not used as a resource block in the LTE system. For example, the (legacy) LTE band may be configured to have a guard-band of at least 100 kHz at the end of each LTE band, and with two non-contiguous guard-bands for 200 kHz for NB-IoT may be used.

As described above, the in-band system and the guard-band system may be operated in a structure in which NB-IoT coexists in the (legacy) LTE band.

By contrast, the stand-alone system may refer to a system or mode that is configured independently of the legacy LTE band. The stand-alone system may be operated by separately allocating frequency bands (e.g., reassigned GSM carriers in the future) used in a GERAN (GSM EDGE radio access network).

The three operation modes described above may be operated independently of each other, or two or more operation modes may be operated in combination.

NB-IoT Signal Transmission/Reception Process

FIG. 33 is a diagram illustrating an example of physical channels that may be used for NB-IoT and a general signal transmission method using the same. In a wireless communication system, an NB-IoT UE may receive information from a BS through a downlink (DL) and the NB-IoT UE may transmit information to the BS through an uplink (UL). In other words, in the wireless communication system, the BS may transmit information to the NB-IoT UE through the downlink and the BS may receive information from the NB-IoT UE through the uplink.

The information transmitted/received by the BS and the NB-IoT UE includes data and various control information, and various physical channels may exist depending on the type/purpose of the information transmitted/received by the BS and NB-IoT UE. The signal transmission/reception method of the NB-IoT may be performed by the above-described wireless communication devices (e.g., BS and UE).

The NB-IoT UE, which is powered on again or enters a new cell, may perform an initial cell search operation such as adjusting synchronization with the BS, or the like (S11). To this end, the NB-IoT UE receives NPSS and NSSS from the BS, performs synchronization with the BS, and acquires cell identity information. Also, the NB-IoT UE may receive the NPBCH from the BS and acquire the in-cell broadcast information. In addition, the NB-IoT UE may receive a DL RS (downlink reference signal) in the initial cell search step to check a downlink channel state.

After completion of the initial cell search, the NB-IoT UE may receive the NPDCCH and the corresponding NPDSCH to acquire more specific system information (S12). In other words, the BS may transmit more specific system information by transmitting the NPDCCH and corresponding NPDSCH to the NB-IoT UE after completion of the initial cell search.

Thereafter, the NB-IoT UE may perform a random access procedure to complete connection to the BS (S13 to S16).

Specifically, the NB-IoT UE may transmit a preamble to the BS via the NPRACH (S13). As described above, the NPRACH may be configured to be repeatedly transmitted on the basis of frequency hopping or the like to enhance coverage or the like. In other words, the BS may (repeatedly) receive a preamble through the NPRACH from the NB-IoT UE.

Thereafter, the NB-IoT UE may receive a random access response (RAR) for the preamble from the BS through the NPDCCH and the corresponding NPDSCH (S14). In other words, the BS may transmit the RAR for the preamble to the NB-IoT UE through the NPDCCH and the corresponding NPDSCH.

Thereafter, the NB-IoT UE transmits the NPUSCH to the BS using scheduling information in the RAR (S15), and may perform a contention resolution procedure such as the NPDCCH and the corresponding NPDSCH (S16). In other words, the BS may receive the NPUSCH from the UE using the scheduling information in the NB-IoT RAR, and perform the contention resolution procedure.

The NB-IoT UE that has performed the above-described process may perform NPDCCH/NPDSCH reception (S17) and NPUSCH transmission (S18) as a general uplink/downlink signal transmission process. In other words, after performing the above-described processes, the BS may perform NPDCCH/NPDSCH transmission and NPUSCH reception as a general signal transmission/reception process to the NB-IoT UE.

In the case of NB-IoT, as mentioned above, NPBCH, NPDCCH, NPDSCH, and the like may be repeatedly transmitted for coverage improvement and the like. In the case of NB-IoT, UL-SCH (i.e., general uplink data) and uplink control information may be transmitted through the NPUSCH. Here, the UL-SCH and the uplink control information (UCI) may be configured to be transmitted through different NPUSCH formats (e.g., NPUSCH format 1, NPUSCH format 2, etc.).

Also, the UCI may include HARQ ACK/NACK (Hybrid Automatic Repeat and reQuest Acknowledgement/Negative-ACK), SR (Scheduling Request), CSI (Channel State Information), and the like. As described above, the UCI in the NB-IoT may generally be transmitted via the NPUSCH. Also, in response to a request/instruction from the network (e.g., BS), the UE may transmit the UCI via the NPUSCH in a periodic, aperiodic, or semi-persistent manner.

Hereinafter, the wireless communication system block diagram shown in FIG. 1 will be described in detail.

N. WIRELESS COMMUNICATION DEVICE

Referring to FIG. 1, a wireless communication system includes a first communication device 910 and/or a second communication device 920. ‘A and/or B’ may be interpreted to have the same meaning as ‘includes at least one of A or B.’ The first communication device may represent a BS and the second communication device may represent a UE (alternatively, the first communication device may represent a UE and the second communication device may represent a BS).

The first and second communication devices may include processors 911 and 921, memories 914 and 924, one or more Tx/Rx RF modules 915 and 925, Tx processors 912 and 922, Rx processors 913 and 923, and antennas 916 and 926, respectively. The Tx/Rx module is also called a transceiver. The processor implements the functions, procedures and/or methods discussed above. More specifically, in the DL (communication from the first communication device to the second communication device), a higher layer packet from the core network is provided to the processor 911. The processor implements the function of a layer 2 (i.e., L2) layer. In the DL, the processor multiplexes a logical channel and a transport channel, provides radio resource allocation to the second communication device 920, and is responsible for signaling to the second communication device. A transmission (TX) processor 912 implements various signal processing functions for the L1 layer (i.e., the physical layer). The signal processing function facilitates forward error correction (FEC) in the second communication device, and includes coding and interleaving. The encoded and interleaved signals are scrambled and modulated into complex-valued modulation symbols. For modulation, BPSK (Quadrature Phase Shift Keying), QPSK (Quadrature Phase Shift Keying), 16QAM (quadrature amplitude modulation), 64QAM, 246QAM, and the like may be used. The complex-valued modulation symbols (hereinafter referred to as modulation symbols) are divided into parallel streams, each stream being mapped to an OFDM subcarrier and multiplexed with a reference signal (RS) in the time and/or frequency domain, and combined together using IFFT (Inverse Fast Fourier Transform) to create a physical channel carrying a time domain OFDM symbol stream. The OFDM symbol stream is spatially precoded to produce multiple spatial streams. Each spatial stream may be provided to a different antenna 916 via a separate Tx/Rx module (or transceiver, 915). Each Tx/Rx module may upconvert each spatial stream into an RF carrier for transmission. In the second communication device, each Tx/Rx module (or transceiver, 925) receives a signal of the RF carrier via each antenna 926 of each Tx/Rx module. Each Tx/Rx module restores the RF carrier signal to a baseband signal and provides it to the reception (RX) processor 923. The RX processor implements various signal processing functions of the L1 (i.e., the physical layer). The RX processor may perform spatial processing on the information to recover any spatial stream directed to the second communication device. If multiple spatial streams are directed to the second communication device, they may be combined into a single OFDMA symbol stream by multiple RX processors. The RX processor transforms the OFDM symbol stream, which is a time domain signal, into a frequency domain signal using a fast Fourier transform (FFT). The frequency domain signal includes a separate OFDM symbol stream for each subcarrier of the OFDM signal. The modulation symbols and the reference signal on each subcarrier are recovered and demodulated by determining the most likely signal constellation points sent by the first communication device. These soft decisions may be based on channel estimate values. Soft decisions are decoded and deinterleaved to recover data and control signals originally transmitted by the first communication device on the physical channel. The corresponding data and control signals are provided to the processor 921.

The UL (communication from the second communication device to the first communication device) is processed in the first communication device 910 in a manner similar to that described in connection with a receiver function in the second communication device 920. Each Tx/Rx module 925 receives a signal via each antenna 926. Each Tx/Rx module provides an RF carrier and information to RX processor 923. The processor 921 may be related to the memory 924 that stores program code and data. The memory may be referred to as a computer-readable medium.

The control method and system of the moving agent group according to the present disclosure may use the platooning of the moving agent group to grasp the situation inside the building in real time. Further, the moving agent detecting the event transfers the group control authority to the following moving agent such that a new moving agent group may be used to continuously search for the interior of the building.

Further, in accordance with the present disclosure, the moving agent that has transferred a group control authority leaves its group and transmits the acquired information at the event occurrence point, such that the detection of events and the search for the remaining regions in the building may be done separately during platooning. Therefore, the situation of the accident (event) occurrence point and the situation of the other regions may be received in real time, such that the current situation of the building and the cause of the accident can be grasped in various ways.

Further, in accordance with the present disclosure, a moving agent that has completed the transmission of event (accident) related information joins back the platooning moving agent group, such that the number of moving agents in the group may be kept constant. Therefore, it is possible to effectively cope with various accidents occurring in the plurality of points in a building.

Further, in accordance with the present disclosure, each of a plurality of moving agent groups may platoon. Thus, the moving agent group can be efficiently managed considering the complexity of the building and the total number of moving agents.

Further, in accordance with the present disclosure, a map may be created using information obtained via the platooning of the moving agent groups. Thus, the situation of the building may be grasped in various ways and further the cause of the accident in the blind spot which cannot be grasped by the existing CCTV may be identified.

Further, in accordance the present disclosure, the identification of the internal situation and accident points of the building may be completed be before the workforce for coping with the accident are deployed. This may reduce the human power and economic resources required to understand the situation inside the building, and may minimize the human damage by utilizing the information as obtained.

Hereinafter, a control system and a control method of a moving agent group according to the present disclosure will be described with reference to the accompanying drawings.

FIG. 34 is a diagram for describing the configuration of a control system of a moving agent group according to an embodiment of the present disclosure. The moving agent group may monitor the situation inside the building.

Referring to FIG. 34, the control system may include a server 100, a plurality of moving agents 200-1, 200-2, . . . and a camera 300.

The server 100 manages a plurality of moving agents 200-1, 200-2, . . . over wireless communication. Specifically, the server 100 may group the plurality of moving agents 200-1, 200-2, . . . into at least one group for management thereof. The server 100 may assign a group control authority to one moving agent 200 among the plurality of moving agents 200-1, 200-2, . . . .

According to one embodiment, the server 100 may assign the group control authority to two or more moving agents 200, respectively. In this case, the number of moving agent groups may be two or more so as to correspond to the number of group control authorities as granted.

According to one embodiment, when the server 100 receives group reconstruction data to be described later, the server may reconstruct the current moving agent group.

Specifically, the server 100 may combine two or more moving agent groups into one moving agent group, or divide one moving agent group into multiple moving agent groups. Further, the server 100 may control the moving agent 200 that has completed transmission of the event-related information as described later to join another moving agent group.

The server 100 may communicate with the moving agent 200 to allow the moving agent group to initiate platooning and may send and receive various information required for platooning with the moving agent 200.

Specifically, the server 100 sends travel-related information to the moving agent group. The travel-related information may include at least one of a map and information about a target point inside the building and information about preset events. The preset events may include at least one of the building collapses, fire, or human accidents.

The server 100 may grant the group control authority by sending group control authority data to the corresponding moving agent 200. The group control authority data may include at least one of the ID and the current position of each moving agent 200 belonging to the corresponding group.

The server 100 may receive data from the moving agent 200 to update the situation within the building and control the moving agent group. Specifically, the server 100 communicates with the first moving agent 200 as the moving agent 200 having the group control authority in each group, thereby to update the situation in the building in real time. The server 100 may receive the travel data according to the platooning from the first moving agent to generate the 3D map in the building in real time.

The travel data may include at least one of the map of the travel path of the first moving agent and the image acquired using the travel path.

According to one embodiment, the server 100 may receive the travel data from each of two or more moving agent groups to generate the 3D map. The server 100 may generate the 3D map for each group so that the travel path is identified for each moving agent group.

The server 100 may receive the event-related information from a later-described third moving agent and update the 3D map.

The plurality of moving agents 200-1, 200-2, . . . platoon along the path inside the building. Specifically, each moving agent 200 may operate as a first moving agent or a second moving agent depending on whether the group control authority is assigned thereto.

When the moving agent 200 is granted the group control authority, the corresponding moving agent 200 operates as the first moving agent.

The first moving agent may control the platooning of the moving agent group to which the first moving agent belongs. Specifically, the first moving agent moves while being positioned at a leading or frontmost position of the group. The first moving agent uses the travel-related information received from server 100 to determine the path and initiate the travel. The first moving agent sends platooning-related information to the second moving agent as a moving agent 200 belonging to its group. The platooning-related information may include at least one of the information about the current position, operation and movement path of the first moving agent.

The first moving agent may determine whether the group reconstruction requirement is met and send the determination result to the server 100. Specifically, the first moving agent may transmit group reconstruction data to the server 100 so that its group is divided into two or more moving agent groups or merged with another moving agent group.

The first moving agent may generate travel data using the acquired information while travelling and may transmit the travel data to the server 100. When the first moving agent 200 detects the preset event, the first moving agent 200 may transfer the group control authority to the second leading moving agent as the next following moving agent. The first moving agent that has transferred the group control authority may operate as a third moving agent.

The third moving agent leaves its group and acquires information about the detected event. The third moving agent sends event-related information to the server 100. When the situation regarding the event is terminated, the third moving agent may join the moving agent group that is currently traveling. The event-related information may include at least one of the image of the position at which the event occurred and the type of the event.

Specifically, when the third moving agent determines that the event is terminated, the third moving agent may transmit a join request to server 100. The server 100 transmits the information of the moving agent group currently traveling to the third moving agent.

The information of the moving agent group includes the ID of each moving agent group (for example, G1, G2 . . . ), the ID and position of the first moving agent belonging to each group, and the ID and position of each second moving agent belonging to each group.

According to one embodiment, the third moving agent may join a moving agent group positioned closest to itself using the information about the moving agent group as received.

When the group control authority is not granted to a moving agent 200, the corresponding moving agent 200 operates as the second moving agent. The second moving agent follows the first moving agent and performs platooning.

Specifically, the second moving agent may receive platooning-related information from the first moving agent of the group to which it belongs which has been received from the server 100. The platooning-related information may include at least one of the ID and the current position and operation of the first moving agent.

The second moving agent may follow the first moving agent using the platooning-related information.

According to one embodiment, the second moving agent may follow other operations other than the movement of the first moving agent using the platooning-related information. The other operations may be one of the possible operations according to the specification of the moving agent 200. For example, when the moving agent 200 has a cleaning function, the second moving agent following the operation of the first moving agent may drive the motor to rotate the brush or draw in the dust.

When the second moving agent receives a group control authority from the first moving agent in its group, the second moving agent may act as a new first moving agent in the group to lead the movement of the following moving agents in its group and control the platooning.

The camera 300 may include a camera installed in the building. For example, the camera 300 may include a plurality of CCTV (closed circuit television cameras) installed in the building, an infrared thermal sensing camera, and the like as installed in the building. The camera 300 may transmit the captured image to the server 100 or the moving agent 200.

In the embodiment of the present disclosure, the control system of the moving agent group may use platooning of the plurality of moving agents 200-1, 200-2 . . . to grasp the situation inside the building in real time. Upon detecting the accident, the first moving agent transfers the group control authority to the following second moving agent. Thus, a new moving agent group may be used to continuously search for the interior of the building.

Further, in accordance with the present disclosure, a moving agent that has transferred a group control authority leaves its group and transmits the information acquired at the accident occurrence point to the server. Thus, a report of the accident detected during platooning and a search for the remaining regions within the building may be made separately. Therefore, the situation of the accident occurrence point and the situation of the other areas may be received by the server in real time, and thus the current situation of the building and the cause of the accident may be grasped by the server in various ways.

Further, in accordance with the present disclosure, the moving agent that has completed the transmission of the accident occurrence-related information (event-related information) joins the platooning moving agent group. Thus, the number of the moving agents in the group may be kept constant. Therefore, it is possible to effectively cope with various accidents occurring in the plurality of points in the building.

FIG. 35 is a diagram for describing the configuration of a moving agent according to another embodiment of the present disclosure.

Referring to FIG. 35, a moving agent 200 according to another embodiment of the present disclosure includes a travel driver 210, a communication unit 220, an object recognition unit 230, a position recognition unit 240, an obstacle recognition unit 250, a power supply 260 and a controller 270.

The moving agent 200 may platoon together with a plurality of other moving agents 200 to monitor the interior of the building. According to one embodiment, the moving agent 200 may monitor the inside of the building and, at the same time, clean the inside of the building along the movement path. The plurality of other moving agents 200 may include at least one of a first moving agent having a group control authority and a second moving agent having no group control authority.

Specifically, the travel driver 210 provides the driving force for the moving agent 200 to move along the travel path within the building. Using the driving force, the moving agent 200 may move on the ground or in the air.

Specifically, the travel driver 210 may include a motor and a motor driver for driving the motor. According to one embodiment, the motor may be implemented as a wheel motor connected to wheels or a propeller driving motor connected to a propeller.

According to one embodiment, the travel driver 210 may include at least one of a brush motor and a suction motor for cleaning the interior of the building.

The communication unit 220 may send and receive data for the moving agent 200 to perform platooning together with a plurality of other moving agents 200.

The communication unit 220 may communicate with the server 100 and other moving agents 200.

1) The data sent to the server 100 may include the current position of the moving agent 200 and travel data generated while the moving agent 200 travels.

2) Data received from the server 100 may include group control authority data and travel-related information.

3) Data transmitted/received between the moving agents 200 may include the current position of moving agent 200, platooning-related information generated using the travel-related information, and the group control authority data.

The object recognition unit 230 may acquire an image on the travel path of the moving agent 200 and detect a predetermined event. The preset events may include at least one of the building collapses, human damages, and fires. The object recognition unit 230 may be implemented as a sensor and a camera for detecting a person or an object.

The position recognition unit 240 may detect the position of the moving agent 200 by detecting the surrounding information. According to one embodiment, the position recognition unit 240 may create a map within the building. The information of the map inside the building may be included in the travel data.

The obstacle recognition unit 250 may detect an obstacle present on the travel path of the moving agent 200 within the building.

Herein, each of the object recognition unit 230, the position recognition unit 240, and the obstacle recognition unit 250 may be referred to as a sensor unit for sensing a situation inside the building. The situation inside the building may include at least one of the information related to the event, the map inside the building, and the current position of the moving agent 200.

The power supply 260 may provide power for driving the moving agent 200. Specifically, the power supply 260 may include a battery driver and battery.

The controller 270 determines the presence or absence of the group control authority and controls the moving agent 200 to operate as the first moving agent or the second moving agent based on the determination result.

Specifically, when the moving agent 200 has the group control authority granted from the server 100 or has received from another moving agent 200, the controller 270 controls the moving agent 200 to operate as the first moving agent.

The operation of the first moving agent will be described in detail below.

The controller 270 controls the group moving such that the first moving agent is positioned in front of the second moving agents included in the group and leads the second moving agents. Specifically, the controller 270 determines a travel path for moving inside the building using the travel-related information received from the server 100, and controls the travel driver 210 to move along the travel path. In this connection, the controller 270 may transmit platooning-related information including the travel path and the current position of the first moving agent to the second moving agent included in its group.

The controller 270 controls the first moving agent to generate travel data and transmit the data to the server 100 when traveling along the travel path. Specifically, the controller 270 controls the object recognition unit 230 to acquire an image on the travel path. The controller 270 may control the position recognition unit 240 to determine the current position and generate a map according to travel progression.

The controller 270 generates travel data including at least one of the image on the travel path, the current position, and the travel history map. Then, the controller 270 may control the communication unit 220 to transmit the generated travel data to the server 100.

When the first moving agent detects the event, the controller 270 may control the first moving agent to transfer the group control authority to the just next following second agent in the plurality of other moving agents 200.

Specifically, when the object recognition unit 230 determines that the event has occurred, the controller 270 receives the current position of each of the second moving agents included in its own group. The controller 270 controls the communication unit 220 to transmit the group control authority data to the second moving agent in the closest position to the current first moving agent. At this time, the controller 270 may destroy its own group control authority data. The controller 270 passes the previous history of the group control authority data to the server 100. The previous history may include the ID and the current position of the corresponding second moving agent that received the group control authority data, and the ID and current position of each of the remaining moving agents included in the corresponding group.

According to one embodiment, the controller 270 may control the moving agent 200 that has transferred the group control authority data to operate as the third moving agent.

The operation of the third moving agent is described below.

The controller 270 may control the third moving agent to send information about events as previously detected by the third moving agent to the server 100. Specifically, the controller 270 may control the travel driver 210, the object recognition unit 230, and the position recognition unit 240 so that the third moving agent acquires information on the event in various angles. The controller 270 may generate event-related information including information about at least one of the position at which the event occurred, the image at the position where the event occurred, and the type of the event. The controller 270 may control the communication unit 220 to send the event-related information to the server 100.

The controller 270 may determine whether a situation associated with the event has been terminated. For example, a case may be assumed where a professional worker arrives at the spot where the event occurred and copes with the event. In this connection, the controller 270 may receive information about the corrected state from the server 100 and determine that the situation related to the event has been terminated.

When the controller 270 determines that the situation associated with the event has been terminated, the controller 270 may control the third moving agent to terminate the transmission of the event-related information and to join one of at least one moving agent group currently travelling.

Specifically, the controller 270 controls the communication unit 220 to send a join request into another moving agent group to the server 100. The third moving agent 200 may receive information of the moving agent groups currently platooning from the server 100.

The information of the moving agent groups may include the ID of each group (for example, G1, G2 . . . ), the ID and current position of the first moving agent belonging to each group, and the ID and current position of each second moving agent belonging to each group.

The controller 270 may select any first moving agent among the first moving agents belonging to the respective groups using the information of the moving agent groups that has been received by the controller 270. The controller 270 may control the third moving agent to operate as the second moving agent that follows the selected first moving agent.

With regard to the selection of the first moving agent, the controller 270 selects the first moving agent based on the current progress of the platooning within the building, the number of second moving agents included in each group, and the distance to each group.

According to one embodiment, the controller 270 may select the first moving agent closest to the current position of the third moving agent among the first moving agents belonging to the groups.

According to one embodiment, the controller 270 may select a first moving agent designated by the server 100.

When the group control authority is absent on the moving agent 200, The controller 270 control the moving agent 200 to operate as the second moving agent.

The operation of the second moving agent is described below.

The second moving agent may receive information of the first moving agent having a group control authority for its group from the server 100. The controller 270 may control the second moving agent to follow the first moving agent.

According to one embodiment, the controller 270 may control the second moving agent to follow other operations of the first moving agent in addition to the movement of the first moving agent. Specifically, when the first moving agent travels inside the building and, at the same time, uses a brush or vacuum motor to clean the floor, the controller 270 may control the second moving agent to travels inside the building and, at the same time, to use a brush or vacuum motor to clean the floor.

The controller 270 may periodically determine whether the second moving agent has a group control authority. When the second moving agent has received the group control authority from the first moving agent during travel, the controller 270 may control the second moving agent to operate as the first moving agent in its group. The operation of the first moving agent is the same as described above.

In accordance with the present disclosure, the moving agent may act as the first moving agent or the second moving agent depending on the presence or absence of the group control authority. The platooning can be performed efficiently based on the transfer of the group control authority.

Further, in accordance with the present disclosure, the first moving agent that senses the event transfers the group control authority to the second moving agent, such that a new moving agent group may be used to continuously search for the interior of the building.

Further, according to the present disclosure, the first moving agent that has transferred the group control authority leaves its group and acts as the third moving agent and then transmits the acquired information at the event occurrence position to the server. Thus, the detection of events and the search for the remaining regions in the building during platooning may be done separately. Therefore, the current situation of the building and the cause of the accident can be grasped in multiple ways by receiving the situation of the accident occurrence point and the situation of the other regions in real time.

Further, according to the present disclosure, the third moving agent that has completed the transmission of event-related information joins the moving agent group in platooning. Thus, the number of the moving agents in the group may be kept constant. Therefore, it is possible to effectively cope with various accidents occurring in the plurality of points in a building.

Each component of the moving agent 200 may be implemented by including various components, sensors, motors, and/or cameras that may perform corresponding functions. Hereinafter, the detailed configuration of the moving agent 200 as implemented according to one embodiment will be described with reference to FIG. 36.

FIG. 36 is a diagram for describing the detailed configuration of a moving agent according to another embodiment of the present disclosure.

Referring to FIG. 36, the travel driver 210 may be implemented to include a motor driver 211, a wheel motor 212, a rotary motor 213, a brush motor 214, and a suction motor 215.

The motor driver 211 may drive the wheel motor 212, the rotary motor 213, the brush motor 214, and the suction motor 215. The wheel motor 212 may drive a plurality of wheels to travel inside the building. The rotary motor 213 may be driven for left and right rotation, up and down rotation of the wheel of the main body or head of the moving agent 200 or for the turn of the wheels. The brush motor 214 may drive brushes that sweep up dirt and dust on the floor or wall surface inside the building. The suction motor 215 may be driven to suck up the dirt or dust.

The communication unit 220 may be implemented to include an LTE router 221 and a WIFI SSID 222. The LTE router 221 may perform LTE communication for transmitting and receiving data with the server 100 and other moving agents 200. The WIFI SSID 222 may perform position identification of a specific object or moving agent 200 by analyzing the signal strength of the WiFi.

The object recognition unit 230 may be implemented to include a recognized data treatment module 231, a 2D camera 232, and an RGBD camera 233.

The 2D camera 232 may be a sensor for recognizing a person or an object based on a two-dimensional image. The RGBD camera 233 may be a sensor for detecting a person or object using captured images having depth data acquired from a camera with RGBD (Red, Green, Blue, Distance) sensors, or other similar 3D imaging devices. The recognized data treatment module 231 may process signals such as 2D image/video or 3D image/video obtained from the 2D camera 232 and the RGBD camera 233 to determine the occurrence of the event and determine the type of the event.

The position recognition unit 240 may be implemented to include a rider 241, and a SLAM camera (a simultaneous localization and mapping camera) 242. The light detection and ranging (Lidar) 241 may be a laser radar and may be a sensor that performs position recognition by irradiating a laser beam and by collecting and analyzing backscattered light among light absorbed or scattered by the aerosol.

The SLAM camera 242 may implement the concurrent position tracking and map generation techniques. The moving agent 200 detects the surrounding information using the SLAM camera 242 and processes the obtained information to create a map corresponding to the region in which the navigation is completed while travelling inside the building, and further estimates the absolute location thereof.

The obstacle recognition unit 250 may be implemented to include USS 251, Cliff PSD 252, ARS 253, Bumper 254, and OFS 255.

The USS (Ultrasonic sensor) 251 may include a sensor to determine the distance between the obstacle and moving agent 200 in the building using ultrasonic signals.

The Cliff PSD 252 may include a sensor to detect cliffs in a travel range in front of the moving agent 200 around 360 degrees.

The ARS (Attitude Reference System) 253 may include a sensor capable of detecting the attitude of the moving agent 200. The ARS 253 may include sensors configured with three acceleration axes and three gyro axes for detecting the amount of rotation of the moving agent 200. Sensors included in the bumper 254 may detect collisions between the moving agent 200 and obstacles in the 360 degrees range.

The OFS (Optical Flow Sensor) may include a sensor that can measure the free wheel of the moving agent 200 and the travel distance of the moving agent 200 on various floors.

The battery driver 262 may be implemented to include a lithium-ion battery 261 and a batter driver. The lithium-ion battery 261 may be configured by connecting two 24V/102 A lithium-ion batteries in parallel. The battery driver 262 may manage the charging and discharging of the lithium-ion battery 261.

The controller 270 may be implemented to include the AP 271 and the microcomputer 272.

The AP (Application Processor) 271 may function as a central processing unit that manages the entire system of hardware modules of the moving agent 200. The AP 271 may drive the application program for traveling using the position information input by using various sensors, and transmit the resulting control signal to the microcomputer 272 so as to drive the motor.

The microcomputer 272 may manage operations of the power supply 260, travel driver 210, and obstacle recognition unit 250 according to the control signals received from AP 271.

An implementation of the moving agent 200 according to the present disclosure may include the following embodiments.

In one embodiment, a moving agent platooning together with a plurality of other moving agents within the building may include a travel driver for moving the agent along the travel path within the building, a communication unit for transmitting and receiving data for performing the platooning, a sensor unit for sensing information related to an event preset on the travel path, and a controller. The controller may be configured as follows: when the moving agent has a group control authority, the controller may control the moving agent to act as the first moving agent to control the platooning; and when the moving agent does not have the group control authority, the controller may control the moving agent to act as the second moving agent to follow another moving agent with the group control authority among the plurality of other moving agents.

In an embodiment, when the moving agent having the group control authority detects the event, the controller may control the moving agent to transfer the group control authority to the just next following second leading moving agent among the plurality of other moving agents.

In an embodiment, the communication unit receives group control authority data from the server and travel-related information for the building. The controller uses the travel-related information to control the travel driver. The controller uses the group control authority data to control the communication unit to transmit the platooning-related information to a second moving agent among the plurality of other moving agents belonging to the same group.

In an embodiment, when the moving agent transfers the group control authority, the controller controls the moving agent to act as a third moving agent and to send the event-related information to the server and to join, as the second moving agent, into the plurality of moving agents currently platooning.

In an embodiment, when the moving agent has a group control authority, the controller may control the moving agent to generate the travel data using the sensing information from the sensor unit while the moving agent travels, and may control the communication unit to transmit the travel data to the server. The travel data is characterized by including at least one of the map about the travel path of the moving agent and the image acquired using the travel path.

With regard to the building in which the moving agent 200 is deployed, a reference is below made to FIG. 37.

FIG. 37 is a plan view to describe the building in which the moving agent group is deployed.

Referring to FIG. 37, a moving agent group that includes a plurality of moving agents is placed at the inlet of the building. The group includes a first moving agent and three second moving agents.

According to one embodiment, the group may be configured to have a first moving agent and at least one second moving agent or to have a first moving agent and a third moving agent which has transferred the group control authority.

FIG. 37 shows a state after a server 100 grants a group control authority to a moving agent among moving agents belonging to a group but before the group starts to travel.

A target region in which the platooning of the moving agents is performed may be all of floors of the building or a specific floor of the building, or only a specific zone of the specific floor. However, the target area is not limited thereto. The target area may be specifically specified while being included in the travel-related information received by the first moving agent from the server 100.

The control method of the moving agent group platooning in the inside of the building is described in detail below.

FIG. 38 is a flow chart for describing the control method of the moving agent group according to another embodiment of the present disclosure.

Referring to FIG. 38, a control method of a moving agent group according to another embodiment of the present disclosure may include a step S2000 for detecting occurrence of an event, and a step S2100 for transferring a group control authority. According to one embodiment, the control method may include step S2200 for reporting an event, and step S2300 for joining another group.

In S2000, while a plurality of moving agents are platooning, the first moving agent leading the platooning detects the occurrence of a predetermined event.

The plurality of moving agents are grouped into at least one group, and each group may include the first moving agent and at least one second moving agent. The first moving agent is a moving agent having a group control authority corresponding to the group which the first moving agent belong to. A moving agent without the group control authority is the second moving agent.

The predefined events may include at least one of the building collapses, human damage, and fires. However, the present disclosure is not limited thereto. The predetermined event may be specifically set according to the characteristics of the target building in which the group is platooning.

In S2100, the first moving agent transfers the group control authority to the just next following moving agent except the first moving agent among the plurality of moving agents.

The second moving agent may follow the first moving agent belonging to its group. According to one embodiment, the second moving agent may travel while following the operation of the first moving agent.

When the second moving agent has received the group control authority from the first moving agent, the second moving agent may operate as a new first moving agent in the corresponding group. Specifically, the second moving agent as a new first moving agent may lead the movement of the remaining second moving agents following the second moving agent.

In S2200, the first moving agent that has transferred the group control authority may act as the third moving agent and may send event-related information as previously detected to the server 100.

Specifically, the first moving agent that has transferred the group control authority may send the previous history of the group control authority to the server 100 and discard its group control authority. The first moving agent leaves the own group and acts as the third moving agent which belongs to a separate group and is managed by the server 100.

The third moving agent stops at a time point where the event is detected and acquires the event-related information. The event-related information may include at least one of the position at which the event occurred, the image at the position where the event occurred, and the type of the event. Until the event-related situation is terminated, the third moving agent may keep sending the event-related information to the server 100.

In S2300, the third moving agent may join, as a second moving agent, to at least one of the moving agent groups currently platooning. Specifically, the third moving agent that has sent the event-related information sends a join request to the server 100. The third moving agent may receive from the server 100 information about the moving agent group that is currently platooning.

The information about the moving agent group may include the ID of each group (for example, G1, G2 . . . ), the ID and current position of the first moving agent belonging to each group, and the ID and current position of each second moving agent belonging to each group.

The third moving agent may select one of the first moving agents belonging to the groups using the information about the moving agent group and then may operate as a second moving agent that follows the corresponding selected first moving agent.

According to one embodiment, the third moving agent may operate as a second moving agent following the first moving agent as designated by the server 100.

In one embodiment, the third moving agent may operate as a second moving agent that follows the first moving agent closest to its current position.

As described above, the control method and system of the moving agent group according to the present disclosure may use the platooning of the moving agent group to grasp the situation inside the building in real time. Further, the moving agent detecting the event transfers the group control authority to the following moving agent such that a new moving agent group may be used to continuously search for the interior of the building.

Further, in accordance with the present disclosure, the moving agent that has transferred a group control authority leaves its group and transmits the acquired information at the event occurrence point, such that the detection of events and the search for the remaining regions in the building may be done separately during platooning. Therefore, the situation of the accident (event) occurrence point and the situation of the other regions may be received in real time, such that the current situation of the building and the cause of the accident can be grasped in various ways.

Further, in accordance with the present disclosure, a moving agent that has completed the transmission of event (accident) related information joins back the platooning moving agent group, such that the number of moving agents in the group may be kept constant. Therefore, it is possible to effectively cope with various accidents occurring in the plurality of points in a building.

Further, in accordance the present disclosure, the identification of the internal situation and accident points of the building may be completed be before the workforce for coping with the accident are deployed. This may reduce the human power and economic resources required to understand the situation inside the building, and may minimize the human damage by utilizing the information as obtained.

Hereinafter, the sensing step S2000 will be described in more detail with reference to FIG. 39.

FIG. 39 is a flow chart for specifically describing the step of detecting the occurrence of an event in the control method of the moving agent group according to another embodiment of the present disclosure.

Referring to FIG. 39, the sensing step S2000 may include a group forming step S2010, a platooning step S2020, and a sensing step S2030.

In step S2010, the server 100 assigns the group control authority to one of the plurality of moving agents, and transmits travel-related information to the corresponding moving agent having the group control authority to form a moving agent group.

According to one embodiment, the server 100 assigns the group control authority to two or more moving agents among the plurality of moving agents, respectively. Then, the server 100 may transmit the travel-related information the first moving agents to which the group control authority is assigned, thereby to form a plurality of moving agent groups. In this connection, each group control authority may include the information about the second moving agents belonging to a corresponding group among the plurality of moving agents. The server 100 may determine the number of group control authorities with taking into account the area of the building subjected to the platooning, the complexity thereof, and the total number of moving agents.

In accordance with the present disclosure, platooning of a plurality of moving agent groups may be performed. Thus, the moving agent groups may be efficiently managed with considering the complexity of the building and the total number of moving agents.

In S2020, the moving agent with the group control authority is positioned at the head of the group as the first moving agent and travels according to the travel-related information. The remaining moving agents among the plurality of moving agents may act as the second moving agent and follow the first moving agent. The group control authority may include the information about the second moving agents belonging to the corresponding group among the plurality of moving agents.

The first moving agent sends platooning-related information to the second moving agents belonging to its group based on the group control authority. The second moving agents may travel according to the platooning-related information. The platooning-related information may include information about at least one of the ID, current position and operation of the first moving agent.

According to one embodiment, step S2020 may include a group reconstruction step.

In the group reconstruction step, the first moving agent determines whether the group reconstruction requirement is met during travel and sends the determination result to the server 100. Specifically, the first moving agent may send group reconstruction data to the server 100, including information related to whether or not the group is to be divided or merged. Whether the group reconstruction requirements are met may be determined by considering the area within the building, the complexity of the building and the total number of moving agents according to the travel-related information.

When the group reconstruction requirement is met, the server 100 may divide the current moving agent group into a plurality of moving agent groups or merge the current group with another moving agent group.

1) When the group must be divided according to the group reconstruction data, the server 100 may additionally grant the group control authority to at least one moving agent of the plurality of moving agents.

2) When the group should be merged according to the group reconstruction data, the server 100 may control all moving agents that belong to another moving agent group that is currently traveling to be merged, as the second moving agent, in the group corresponding to the first moving agent that transmitted the group reconstruction data.

After the server 100 first forms a moving agent group and after the initiation of platooning, the moving agent group may be reconstructed according to the internal situation of the building. This may improve the efficiency of platooning by managing the moving agent group adaptively according to internal situation of building.

At S2030, the first moving agent senses the occurrence of the predetermined event during being travelling according to the travel-related information. According to one embodiment, the step S2030 may include a data collection step in which the first moving agent generates and transmits travel data to the server 100, and a map creation step in which the server 100 may use the travel data to create a 3D map within the building

The travel data may include at least one of the map of the travel path of the first moving agent and the acquired image using the travel path.

Further, in accordance with the present disclosure, a map may be created using information obtained via the platooning of the moving agent groups. Thus, the situation of the building may be grasped in various ways and further the cause of the accident in the blind spot which cannot be grasped by the existing CCTV may be identified.

In FIG. 40 to FIG. 44, a specific example in which the moving agent group performs the platooning is described along with an internal plan view of the building part.

FIG. 40 is a diagram to describe the operation of the moving agent group in relation to the transfer of the group control authority when a moving agent group detects an event during platooning.

Referring to FIG. 40, there is one moving agent group, and all of moving agents belonging to the corresponding group are four agents 200-1 to 200-4. The remaining moving agents 200-2 to 200-4 except the first moving agent 200-1 may act as the second moving agent.

In FIG. 40a , the first moving agent 200-1 leading the platooning may start to travel. In FIG. 40b , the first moving agent 200-1 detects an event E. The first moving agent 200-1 transfers the group control authority to the second moving agent 200-2 which is the most preceding among the following second moving agents 200-2 to 200-4.

In FIG. 40c , the new first moving agent 200-2 may lead the remaining second moving agents 200-3 and 200-4 and thus continues the platooning toward the remaining regions of the building. The first moving agent 200-1, which has transferred the group control authority, operates as a third moving agent while leaving its own group. The first moving agent 200-1 may transmit the event-related information as information on the detected event E to the server 100.

In FIG. 40d , the third moving agent 200-1 keeps sending the event-related information to the server 100 until the situation related to the event E is terminated

As described above, the group control authority may be transferred to the moving agent 200-2 such that when the event E is detected by the moving agent 200-1 during platooning and information about the event is reported to the server 100, the remaining moving agents 200-2 to 200-4 may continue platooning. Thus, the search for the remaining regions of the building is not delayed.

FIG. 41 is a diagram for describing the operation in which a moving agent which has transferred a group control authority when the moving agent group detects the occurrence of an event during platooning joins back the group.

Referring to FIG. 41a , the first moving agent 200-1 detects the event E and transfers the group control authority to the just next following moving agent 200-2 among the second moving agents 200-2 to 200-4. In this connection, the first moving agent 200-1 may inform the server 100 that the group reconstruction requirement is met. The server 100 may additionally grant a group control authority to the moving agent 200-4 as one of the moving agents in the group in order to separate, from a current group, a group to which the moving agent 200-2 belongs as the first moving agent.

The group reconstruction requirements may be determined by considering the area within the building, the complexity of the building, and the total number of moving agents according to the travel-related information. For example, when the area of the platooning target region is larger than a certain area and the number of moving agents included in the group is greater than a certain number, the current group may be divided into at least two new groups.

Referring to FIG. 41b , there are three moving agent groups managed by the server 100. Specifically, the two groups perform platooning based on the two first moving agents 200-2 and 200-4 respectively. One group has the third moving agent 200-1 that reports the event E.

The first moving agent 200-4 selects a path different from a path of the first moving agent 200-2 belonging to another group according to the travel-related information received from the server 100.

Upon determining that the situation related to event E has been terminated, the third moving agent 200-1 which has completed the transmission of the event-related information to the server may send a join request to the server 100 and in response, may receive the information about the moving agent group currently platooning from the server.

Referring to FIG. 41c , the third moving agent 200-1 selects the first moving agent 200-4 using the information about the moving agent group and may join, as the second moving agent, into the group corresponding to the selected first moving agent and may preform platooning.

According to one embodiment, the third moving agent 200-1 may select the moving agent 200-4 closest to its position as the first moving agent and may join, as the second moving agent, into the group corresponding to the selected first moving agent and may preform platooning.

According to one embodiment, the server 100 may transmit information about the moving agent 200-4 to the third moving agent 200-1 to join the group having a small number of moving agents with considering the number of moving agents included in each moving agent group.

The moving agent that leaves the group upon detecting the event may join the moving agent group again when the condition of the previously detected event is terminated. Therefore, this may prevent the situation in which the platooning is stopped because all the moving agents in the group leave the group when each of all of the moving agent may detect each event and transmit event-related information.

FIG. 42 is a diagram for describing how a plurality of group control authorities are assigned to the moving agents respectively.

Referring to FIG. 42a , according to one embodiment, the server 100 may assign group control authorities respectively to two or more moving agents among the plurality of moving agents 200-1 to 200-4 before the platooning is started, thereby to form a plurality of moving agent groups.

Referring to FIG. 42b , the server 100 may assign the group control authority to each of two moving agents 200-1 and 200-3 among the plurality of moving agents 200-1 to 200-4. The server 100 transmits travel-related information to each of the first moving agents 200-1 and 200-3.

Referring to FIG. 42c , the first moving agents 200-1 and 200-3 lead the second moving agents 200-2 and 200-4 belonging to their groups respectively according to the travel-related information as received and performs the platooning.

When the inside of the building is complicated, there may be a delay in understanding the situation inside the building using one moving agent group. Thus, the server 100 may group the plurality of moving agents 200-1, 200-2, . . . into a plurality of groups, and may allow each group to perform each platooning.

FIG. 43 is a diagram for describing how a moving agent group is divided into a plurality of moving agent groups during platooning.

Referring to FIG. 43a , the first moving agent 200-1 determines whether the group reconstruction requirement is satisfied. When a path is divided into three sub-paths within the building, the first moving agent 200-1 may determine that the group reconstruction (division) requirement is satisfied.

Referring to FIG. 43b , the first moving agent 200-1 sends the group reconstruction data to the server 100 about whether the group reconstruction (division) requirement is met.

The server 100 may assign the group control authority to each of the moving agents 200-3 and 200-4 to divide the current group into three sub groups using the group reconstruction data.

Referring to FIG. 43c , the server 100 may re-transmit travel-related information to each of the first moving agents 200-1, 200-3, and 200-4 when the moving agent groups are reconstructed. Each of the first moving agents 200-1, 200-3, and 200-4 may travel according to the travel-related information as received.

In accordance with the present disclosure, the sever may determine whether the group reconstruction requirements are met in real time and may reconstruct the moving agent groups based on the reconstruction data. Thus, in response to the internal situation of the building which is not reflected into the existing building internal map, the moving agent groups may be adapted and reconstructed thereto, to cope with the internal situation efficiently.

FIG. 44 is a diagram for describing a map generated in real time using a server as a moving agent group is platooning.

FIG. 44a to FIG. 44c are plan views of the building showing a process in which the moving agent group is platooning. FIG. 44d to FIG. 44f are maps as generated by the server 100 in a corresponding manner to FIG. 44a to FIG. 44c respectively. The maps generated by the server 100 in FIG. 44d to FIG. 44f are simplified for illustration by way of example. Each map may be a 3D map created using the travel data transmitted from each first moving agent.

Referring to FIG. 44a and FIG. 44d , one moving agent group G1 performs platooning. The first moving agent 200-1 transmits the generated travel data to the server 100. The server 100 generates the 3D map according to the travel of the group G1.

Referring to FIG. 44b and FIG. 44e , the moving agent group is split into two groups. The first moving agent 200-1 of the first group G1 may lead the second moving agents 200-4 and 200-5 to perform the platooning. In the second group G2, the first moving agent 200-2 may lead the second moving agent 200-3 to perform the platooning. The server 100 updates the 3D map using the travel data received from the first moving agent 200-1 of the group G1 and the travel data received from the first moving agent 200-2 of the group G2, respectively.

Referring to FIG. 44c and FIG. 44f , the first moving agent 200-1 of the first group G1 detected the event E. The first moving agent 200-1 transfers the group control authority to the second moving agent 200-4, which is the most preceding among the following second moving agents 200-4 and 200-5.

The first moving agent 200-1, which has transferred the group control authority, leaves its group G1 and sends, as a third moving agent, the event-related information to the server 100.

The moving agent 200-4, which has received the group control authority, acts as the first moving agent of the third group G3 and leads the moving agent 200-5 to perform platooning. Then, the moving agent 200-4 transmits the travel data to the server 100.

The server 100 receives the travel data from the first moving agent 200-2 of the second group G2, from the first moving agent 200-4 of the third group G3, and event-related information from the third moving agent 200-1. Then, the server may update the 3D map using the travel data and event-related information as received.

The server 100 generates the 3D map using the travel data as received and updates the 3D map using the travel data received from each moving agent group and event-related information received from the third moving agent. Therefore, the situation inside the building can be grasped in real time due to the progress of the platooning

With reference to FIG. 45 to FIG. 48, the control method of the moving agent 200 such that the moving agent 200 operates as the first moving agent or the second moving agent while platooning together with a plurality of other moving agents will be describe specifically.

FIG. 45 is a flow chart for describing the control method of the moving agent according to another embodiment of the present disclosure.

Referring to FIG. 45, the control method of the moving agent according to another embodiment of the present disclosure may include a group control authority grasping step S2400, a second moving agent operation step S2500, and a first moving agent operation step S2600.

At S2400, the controller 270 determines whether the moving agent 200 has the group control authority. The group control authority has the ability to control platooning by leading a plurality of other moving agents. The group control authority may be transferred from a moving agent having the group control authority or the server 100 to another moving agent in the form of group control authority data.

In S2500, when the controller 270 determines that the group control authority is not present in the moving agent 200 S2400, the controller may control the moving agent 200 as the second moving agent following another moving agent having the group control authority among the plurality of other moving agents.

In S2600, the controller 270 determines that the group control authority is present in the moving agent 200 S2400, the controller may control the moving agent 200 as the first moving agent controlling platooning while being at the head of the plurality of other moving agents.

FIG. 46 is a flow chart for describing a detailed operation when a specific moving agent operates as a second moving agent.

Referring to FIG. 46, in S2500, the moving agent 200 initiate to operate as the second moving agent. In S2510, the second moving agent grasps whether a group control authority exists in itself. It is because the group control authority may be received from the first moving agent of the group to which it belongs during travel.

When the group control authority does not exist in the moving agent 200, the second moving agent 200 performs the platooning while following the first moving agent 52520.

When the group control authority exists in the second moving agent 200, the second moving agent initiates to operate as the first moving agent S2600.

FIG. 47 is a flow chart for describing a detailed operation when a specific moving agent operates as a first moving agent.

Referring to FIG. 47, a moving agent 200 that has been determined as having a group control authority or has receive from the first moving agent of the group to which it belongs may initiate to operates as the first moving agent.

In S2610, the first moving agent travels according to the travel-related information received from the server 100 and acquires an image on the travel path.

In S2620, the first moving agent creates a map based on its travel path.

In S2630, the first moving agent recognizes the situation inside the building. Specifically, the first moving agent detects the occurrence of a preset event.

When the event is not detected in S2640, the first moving agent may travel along the travel path according to the travel-related information and send the platooning-related information to the second moving agent belonging to the group to lead the platooning S2650.

The S2610 to S2650 are shown sequentially for convenience of description, but may be executed in a different order. Operations of S2610 to S2650 may be performed simultaneously in parallel using each component performing a corresponding function in the first moving agent.

When the S2610 to S2650 are performed more than once, the first moving agent may generate travel data that includes at least one of the map of the travel path and the acquired image using its travel path and transmit the data to the server 100.

When the first moving agent detects the event in S2640, the operations of S2660 to S2680 may be performed. In S2660, the first moving agent determines the type of event as detected. In S2670, the first moving agent sends group reconstruction data to the server 100 regarding the reconstruction of the group. The group reconstruction data is information about the transfer of the group control authority and may include the information about the second moving agent, which receives the group control authority and thus acts as the first moving agent. The server 100 may update the status of the moving agent group managed by the server using the group reconstruction data.

In S2680, the first moving agent submits its group control authority to the just next following moving agent among the plurality of other moving agents.

The first moving agent that has transferred the group control authority may operate as a third moving agent to report information about the event to the server. The operation of the third moving agent is described below with reference to FIG. 48.

FIG. 48 is a flow chart for describing a detailed operation when a specific moving agent operates as a third moving agent.

The first moving agent that has transferred the group control authority initiates to operate a the third moving agent. Referring to FIG. 48, in S2700, the third moving agent acquires an image of a sensed event. The third moving agent may switch the current direction toward the position where the event occurred, to facilitate the acquisition of the event's image.

In S2710, the third moving agent determines whether the situation associated with the event has been terminated. When the third moving agent determines that the event-related situation has not yet been terminated, in S2720, event-related information is generated by the third moving agent and then transmitted therefrom to the server 100.

The event-related information may include information about at least one of the position at which the event occurred, the image at the position where the event occurred, and the type of the event.

When the third moving agent determines that the situation associated with the event is terminated, in S2730, a join request to another moving agent group is transmitted from the third moving agent to the server 100. Specifically, the third moving agent sends group reconstruction data to the server 100. The group reconstruction data may include information about the division of the moving agent group, a joining thereof into another moving agent group, and a previous history of the group control authority.

The third moving agent may receive information from the server 100 about the moving agent group that is currently platooning. The third moving agent may join, as the second moving agent, to one moving agent group selected using the information about the moving agent group it has received. The third moving agent joining the moving agent group acts as the second moving agent. The operation of the second moving agent is the same as described in FIG. 46.

The control method and system of the moving agent group according to the present disclosure may use the platooning of the moving agent group to grasp the situation inside the building in real time. Further, the moving agent detecting the event transfers the group control authority to the following moving agent such that a new moving agent group may be used to continuously search for the interior of the building.

Further, in accordance with the present disclosure, the moving agent that has transferred a group control authority leaves its group and transmits the acquired information at the event occurrence point, such that the detection of events and the search for the remaining regions in the building may be done separately during platooning. Therefore, the situation of the accident (event) occurrence point and the situation of the other regions may be received in real time, such that the current situation of the building and the cause of the accident can be grasped in various ways.

The above detailed description is to be considered in all respects only as illustrative and not in a limiting sense. The scope of the present disclosure shall be determined by rational interpretation of the appended claims. All changes within the equivalent range of the present disclosure are included in the scope of the present disclosure. 

What is claimed is:
 1. A method for controlling a moving agent group platooning within a building, the method comprising: a sensing step in which a first moving agent among a plurality of moving agents senses an occurrence of a predetermined event during the plurality of moving agents are platooning, wherein the first moving agent leads the platooning of the plurality of moving agents; and a transferring step in which the first moving agent transfers a group control authority to a second moving agent among the plurality of moving agents, wherein the second moving agent just follows the first moving agent; wherein the second moving agent having the group control authority leads movement of remaining moving agents following the second moving agent.
 2. The method of claim 1, wherein the method further comprises a report step in which, upon transferring the group control authority from the first moving agent to the second moving agent, the first moving agent acting as a third moving agent transmits event-related information to a server, wherein the event-related information is about the sensed event.
 3. The method of claim 2, wherein the method further comprises a joining step in which the third moving agent joins, as a second moving agent, into one of moving agent groups currently platooning.
 4. The method of claim 2, wherein the event-related information includes at least one of an event occurrence position, an image of the position, and a type of the event.
 5. The method of claim 1, wherein the sensing step includes: a group formation step in which a server assigns the group control authority to one of the plurality of moving agents and transmits travel-related information to the moving agent having the group control authority assigned thereto; a platooning step in which while the first moving agent as the moving agent having the group control authority is positioned at a frontmost position, the first moving agent travels according to the travel-related information, and a second moving agent as a remaining moving agent free of the group control authority follows the first moving agent; and a sensing step in which the first moving senses the occurrence of the predetermined event during being traveling according to the travel-related information.
 6. The method of claim 5, wherein in the group formation step, the server grants the group control authority to each of two or more moving agents among the plurality of moving agents and transmits the travel-related information to each of the two or more moving agents as the first moving agent having the group control authority assigned thereto, thereby form a plurality of moving agent groups, wherein each group control authority includes information about the second moving agent belonging to each of the moving agent groups.
 7. The method of claim 5, wherein each group control authority includes information about the second moving agent free belonging to each of the moving agent groups, wherein in the platooning step, the first moving agent sends platooning-related information to the second moving agent belonging to a corresponding group according to the group control authority, and the second moving agent travels according to the platooning-related information.
 8. The method of claim 7, wherein the platooning-related information includes at least one of an ID, a current position, a current operation of the first moving agent.
 9. The method of claim 5, wherein the platooning step is configured such that the first moving agent determines whether a pre-set group reconstruction requirement is met during is travelling and sends the determination result to the server, wherein the method further includes a group reconstruction step in which, upon determination that the group reconstruction requirement is met, the server additionally grants the group control authority to at least one of the plurality of moving agents.
 10. The method of claim 5, wherein the sensing step includes: a data collection step in which the first moving agent generates travel data and transmits the travel data to the server; and a map creation step in which the server uses the travel data to create a 3D map within the building; wherein the travel data includes at least one of a map of a travel path of the first moving agent and an image acquired using the travel path.
 11. A system for controlling a moving agent group monitoring an interior of a building, the system comprising: a plurality of moving agents platooning along an internal path of the building; and a server in wireless communication with the plurality of moving agents, wherein the sever is configured to control the plurality of moving agents, wherein the plurality of moving agents includes: a first moving agent having a group control authority and travelling while positioned at a frontmost position of the plurality of moving agents; and at least one second moving agent following the first moving agent, wherein when the first moving agent detects that a predetermined event has occurred while moving along the path, the first moving agent transfers the group control authority to a just following second moving agent, wherein the just following second moving agent has the group control authority and leads movement of following remaining moving agents.
 12. A method for controlling a moving agent platooning together with a plurality of other moving agents within a building, the method comprising: a first step of determining whether the moving agent has a group control authority; a second step in which upon determination that the moving agent does not have the group control authority, the moving agent operate as a second moving agent following another moving agent having the group control authority among the plurality of other moving agents; a third step in which upon determination that the moving agent has the group control authority, the moving agent operate as a first moving agent to control the platooning while being positioned in front of the plurality of other moving agents; a fourth step in which when the first moving agent detects a preset event during being travelling, the first moving agent transfers the group control authority to a just next following moving agent among the other moving agents.
 13. The method of claim 12, wherein the method further comprises: a fifth step in which upon transferring the group control authority, the first moving agent transmits event-related information to a server, wherein the event-related information is about the detected event; and a sixth step in which the first moving agent joins, as the second moving agent, a moving agent group currently platooning.
 14. The method of claim 12, wherein in the third step, the first moving agent generates travel data thereof and transmits the travel data to the server, wherein the travel data includes at least one of a map of a travel path of the first moving agent and an image acquired using the travel path.
 15. The method of claim 12, wherein in the third step, the first moving agent determines whether a pre-set group reconstruction requirement is met during being travelling, and sends the determination result to the server, wherein whether the group reconstruction requirement is met is determined based on an area inside the building, a complexity inside the building, and a total number of moving agents. 